Internally coated webs

ABSTRACT

An improved process is provided for treating a porous web (especially fabric) to produce a novel silicone polymer internally coated web. In the process, a starting curable liquid silicone polymer is coated under pressure upon one surface of the web, and the web is then subjected to localized shear forces sufficient to move the silicone polymer composition into interior portions of the web and to distribute the silicone polymer composition generally uniformly therewithin in such planar region. Excess silicone polymer composition is wiped away from a web surface. Thereafter, the resulting web is heated or irradiated to cure the silicone polymer. Preferably a web is preliminarily impregnated with a fluorochemical. Webs produced by this process are breathable, waterproof or highly water repellent, and flexible.

REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of application Ser. No. 07/319,778filed Mar. 10, 1989, now U.S. Pat. No. 5,004,643, which is acontinuation-in-part of my earlier filed U.S. patent application Ser.Nos. 167,630; 167,643; 167,797; and 167,869 all filed Mar. 14, 1988, allabandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally concerns porous fibrous webs (especiallyfabrics) that are modified in their properties by incorporationthereinto an internal layer of silicone polymer. Such webs are preparedby pressurized impregnation methods.

2. Prior Art

In the prior art, it has been proposed to treat porous webs, especiallyfabrics, with silicone resins and also with fluorochemicals.

Conventional treatments of webs fall into the general categories of (i)surface coatings and (ii) saturations and impregnations.

For example, U.S. Pat. Nos. 3,436,366; 3,639,155; 4,472,470; 4,500,584;and 4,666,765 disclose silicone coated fabrics. Silicone coatings areknown to exhibit relative inertness to extreme temperatures of both heatand cold and to be relatively resistant to ozone and ultraviolet light.Also, a silicone coating can selectively exhibit resistance to soiling,strength enhancement, and/or flame retardancy.

Fluorochemical treatment of webs is known to impart properties, such assoil resistance, grease resistance, and the like.

Prior art fluorochemical and silicone fabric treatment evidently eachcan protect only that side of the fabric upon which they are disposed.Such treatments characteristically significantly alter the hand, ortactile feel, of the treated side. Prior silicone fabric coatingstypically degrade the tactile finish, or hand, of the fabric and givethe coated fabric side a rubberized finish which is not appealing formany fabric uses, particularly garments.

U.S. Pat. No. 4,454,191 describes a waterproof and moisture-conductingfabric coated with a hydrophilic polymer. The polymer is a compressedfoam of an acrylic resin modified with polyvinyl chloride orpolyurethane and serves as a sort of "sponge" soaking up excess moisturevapor.

Other microporous polymeric coatings have been used in prior artattempts to make a garment breathable, yet waterproof.

Various polyorganosiloxane compositions are taught in the prior art thatcan be used for making coatings that impart water-repellency to fabrics.Typical of such teachings is the process described in U.S. Pat. No.4,370,365 which describes a water repellant agent comprising, inaddition to an organohydrogenpolysiloxane, either one or a combinationof linear organopolysiloxanes containing alkene groups, and a resinousorganopolysiloxane containing tetrafunctional and monofunctionalsiloxane units. The resultant mixture is catalyzed for curing anddispersed into an aqueous emulsion. The fabric is dipped in the emulsionand heated. The resultant product is said to have a good "hand" and topossess waterproofness.

This type of treatment for rendering fabrics water repellant withoutaffecting their "feel" is common and well known in the art. However, ithas not been shown that polyorganosiloxanes have been coated on fabricsin such a way that both high levels of resistance to water by thefibers/filaments and high levels of permeability to water vapor areachieved. As used herein, the term "high levels of permeability to watervapor" has reference to a value of at least about 500 gms/m² /day, asmeasured by ASTM E96-80B. Also, as used herein, the term "high level ofwaterproofness" is defined by selective testing methodologies discussedlater in this specification. These methodologies particularly deal withwater resistance of fabrics and their component fibers.

Porous webs have been further shown to be surface coated in, forexample, U.S. Pat. Nos. 4,478,895; 4,112,179; 4,297,265; 2,893,962;4,504,549; 3,360,394; 4,293,611; 4,472,470; and 4,666,765. These surfacecoatings impart various characteristics to the surface of a web, but donot substantially impregnate the web fibers. Such coatings remain on thesurface and do not provide a film over the individual internal fibersand/or yarn bundles of the web. In addition, such coatings on the websurface tend to wash away quickly.

Prior art treatments of webs, by saturation or impregnation also sufferfrom limitations. Saturation, such as accomplished by padbath immersion,or the like, is capable of producing variable concentrations of a givensaturant chemical.

In order to treat a flexible web, by heavy saturation, or impregnation,with a polymer material, such as a silicone resin, the prior art hassuggested immersion of the flexible web, or fabric, in a padbath, or thelike, using a low viscosity liquid silicone resin so that the lowviscosity liquid can flow readily into, and be adsorbed or absorbedtherewithin. The silicone resin treated product is typically arubberized web, or fabric, that is very heavily impregnated withsilicone. Such a treated web is substantially devoid of its originaltactile and visual properties, and instead has the characteristicrubbery properties of a cured silicone polymer.

U.S. Pat. No. 2,673,823 teaches impregnating a polymer into theinterstices of a fabric and thus fully filling the interstices. Thispatent provides no control of the saturation of the fabric. It teachesfull saturation of the interstices of the fabric.

The prior art application of liquid or paste compositions to textilesfor purposes of saturation and/or impregnation is typically accomplishedby an immersion process. Particularly for flexible webs, includingfabric, an immersion application of a liquid or paste composition to theweb is achieved, for example, by the so-called padding process wherein afabric material is passed first through a bath and subsequently throughsqueeze rollers in the process sometimes called single-dip, single-nippadding. Alternatively, for example, the fabric can be passed betweensqueeze rollers, the bottom one of which carries the liquid or pastecomposition in a process sometimes called double-dip or double-nippadding.

Coating at a predetermined thickness can be achieved by usingprecision-controlled deposition of coating material followed by passagethrough a pair of opposed scraping knives. The knives smooth the coatingand maintain the thickness of the coating to a desired thickness. Forexample, it is possible to apply a relatively thick silicone liquidelastomer coating to a rough web, typically of fiberglass, in order tomake architectural fabric as is taught in U.S. Pat. No. 4,666,765. Inthis example, the drag knives are set to a thickness of about 2 to 10mils thicker than the web thickness. This setting, depending on thecoating speed, can yield a base coat thickness of approximately 3 to 12mils thicker than the web thickness.

Various types of coatings, and various coating thicknesses, arepossible. However, a general principle of coating machinery is that thecoating material is swept, or dragged, along the surface of the fabric.No special attention is normally given to any pressured forcing of thecoating into the fabric, therein making the coating also serve as animpregnant. Of course, some coating will be urged into surface regionsof the fabric by the coating process. Generally, however, application ofhigh transversely exerted (against a fiber or web surface) forces at thelocation of the coating deposition and/or smoothing is not desired inthe prior art processes because it is the goal of the prior art coatingprocesses to leave a definite thickness of coating material upon afabric, and not to scrape the fabric clean of surface-located coatingmaterial.

One prior art silicone resin composition is taught by U.S. Pat. Nos.4,472,470 and 4,500,584, and includes a vinyl terminated polysiloxane,typically one having a viscosity of up to about 2,000,000 centipoises at25° C., and a resinous organosiloxane polymer. The composition furtherincludes a platinum catalyst, and an organohydrogenpolysiloxanecrosslinking agent, and is typically liquid. Such composition is curableat temperatures ranging from room temperature to 100° C. or higherdepending upon such variables as the amount of platinum catalyst presentin the composition, and the time and the temperature allowed for curing.

Such compositions may additionally include fillers, including finelydivided inorganic fillers. Silicone resin compositions that are free ofany fillers are generally transparent or translucent, whereas siliconeresin compositions containing fillers are translucent or opaquedepending upon the particular filler employed. Cured silicone resincompositions are variously more resinous, or hard, dependent upon suchvariables as the ratio of resinous copolymer to vinyl terminatedpolysiloxane, the viscosity of the polysiloxane, and the like.

Curing (including polymerization and cross-linking) can encompass thesame reactions. However, in the fabric finishing arts, such terms can beused to identify different phenomena. Thus, controllable and controlledcuring, which is taught by the prior art, may not be the same as controlof crosslinking. In the fabric finishing arts, curing is a process bywhich resins or plastics are set in or on textile materials, usually byheating. Crosslinking may be considered to be a separate chemicalreaction from curing in the fabric finishing arts. Crosslinking canoccur between substances that are already cured. Crosslinking canstabilize fibers, such as cellulosic fibers through chemical reactionwith certain compounds applied thereto. Crosslinking can improvemechanical factors such as wrinkle performance. Polymerization can referto polymer formation or polymer growth.

SUMMARY OF THE INVENTION

This invention relates to a flexible porous web which contains aninternal coating of a silicone polymer composition.

The silicone polymer composition has a viscosity that is sufficient toachieve an internal coating of the web. Generally, the viscosity isgreater than about 1000 centipoise and less than about 2,000,000centipoise. Such composition, when cured, is preferably elastomeric.

Preferably, a fluorochemical is impregnated into the web before thesilicone polymer is applied.

In a web of this invention the quantity of silicone polymer can varywidely. The silicone polymer composition is present in an amount that issufficient to achieve an internal coating of the web. Generally, thisamount is in the range of about 5 to about 200 weight percent of theweight of the untreated web or fibers. When present, the quantity offluorochemical is in the range of about 0.01 to about 5 weight percentof the weight of the untreated web or fibers. When, as is preferred, aweb incorporates both a fluorochemical and a silicone polymer, they arepresent in an amount sufficient to achieve an internal coating of theweb. Generally, the total weight of fluorochemical and silicone polymeris in the range of about 5 to about 200 weight percent of the weight ofthe untreated web.

Notwithstanding the large amount of silicone present in webs of thepresent invention, they surprisingly retain porosity, breathability,flexibility, hand and other characteristics similar to untreated webswhile exhibiting improved characteristics such as water repellancy,rewashability, service life, abrasion resistance and durability.

The porous webs are generally flat or planar. The webs can comprisefibers in the form of monofilaments, yarns, staples, or the like. Theweb can also be comprised of a matrix having open cells or porestherein.

The web may be a fabric which is woven or non-woven with fibers that canbe of any desired composition. The web will generally be tensionable,but not too weak or elastomeric to be processed in accordance with theteachings of the present invention.

The web fibers are preferably comprised of a synthetic organic polymer;however, fibers comprised of natural fibrous materials can be used.Presently preferred synthetic polymers include polyamides (nylons),polyesters, such as polyethylene terephthalate, polyolefins such aspolypropylene and polyethylene, acrylics, regenerated cellulose,cellulose acetates, and the like. When used, presently preferred naturalfibers include cotton, linen, wool, and silk. Blends of these fibers,e.g., polyester/cotton can also be used.

Webs of the present invention contain a curable silicone polymerimpregnant that is present as a film, or coating, or layer within a webthat envelopes at least a portion of the fibers or cell or pore walls ofthe web. The interstices or open cells in the region of the internalcoating, are mostly filled or plugged by impregnant. The outer surfacesof the web are preferably substantially free of impregnant. However, theweb remains breathable and is either water resistant or waterproof. Thethickness of the film, coating or layer is generally in the range of0.01 to 50 microns.

At a microscopic level, a web of the present invention, for example, afabric, can be regarded as being a complex structure, but generally theinternal layer is discernible under microscopic examination as shown inthe accompanying scanning electron microscope photographs that will bediscussed hereinafter.

Silicone polymer which substantially, completely encapsulates a web'sfibers or lines its cell or pore walls and forms an internal layermeans, that the silicone polymer is located mostly upon surface portionsof the interior of the web.

Depending upon the conditions used to produce it, a web produced inaccordance with the present invention can characteristically andpreferably exhibit a soft hand and flexibility that is comparable to thehand and flexibility of the untreated web. In some cases, the differencein hand between the treated and untreated webs may not be perceptible.This is particularly surprising in view of the substantial amount ofsilicone polymer being added to the web. A treated web has abreathability which, by a present preference, can approach that of theuntreated web notwithstanding the relatively large amount of siliconepolymer present.

A silicone polymer composition having a viscosity in the range aboveindicated is used to produce the treated webs. If desired, additives canbe admixed with such a composition to adjust and improve properties ofsuch composition or web, such as viscosity and/or rheology,combustibility, reflectivity, flexibility, conductivity, light fastness,mildew resistance, rot resistance, stain resistance, grease resistance,and the like. In general, a web of this invention exhibits enhanceddurability.

A web of the present invention preserves much, or even substantiallyall, of its original untreated hand even after an extended period of usewhile demonstrating excellent abrasion resistance. In contrast, anuntreated web typically loses its original hand and displays reducedabrasion resistance after an extended period of use. This is achieved bythe formation of an internal layer that prevents new fiber surfaces frombeing exposed, thereby minimizing the amount of untreated surfaces thatdegrade much faster than the treated fibers.

A web of this invention can undergo a large number of machine washingswith detergent without experiencing appreciable or significant change ordeterioration.

The silicone polymer composition prolongs the use and service life of aweb, usually by at least an order of magnitude, depending on suchfactors as web type, extent and type of treatment by the teachings ofthis invention, and the like.

Optionally, and as indicated above, agents or additives carried by thesilicone polymer composition into a web can be stably fixed in the webwith the cured silicone polymer For example, agents such as ultravioletlight absorbers, dulling agents, reflectivity enhancers, and the like,which modify a web's response to light and radiation are desirablylocated substantially upon the surfaces of the web's fibers. When theseagents are incorporated into the enveloping silicone polymer film, itappears that then they are retained where they are deposited.

A present preference in the practice of this invention is to employ asilicone polymer composition that contains a benzophenone.

In addition, the present invention is directed to processes for makingsilicone polymer internally coated webs. Such processes involvetensioning a porous, flexible web, applying a curable silicone polymercomposition thereto, and then moving a generally uniformly appliedlocalized shear force over and against one surface of the tensioned web.The shear force is sufficient to shear thin the silicone polymer, todistribute the silicone polymer composition within the web as aninternal coating in a region extending generally in spaced, parallelrelationship to at least one face of the web and to generally envelopsurface portions of at least some of the web fibers or form a lining ofthe cells or pores of the web. The web is then optionally interveninglystored, or is (preferably) immediately subjected to curing conditions(heat, moisture and/or radiation) which converts the polymer compositionas deposited in the web into a solid elastomeric polymer.

Various other and further features, embodiments, and the like which areassociated with the present invention will become apparent and betterunderstood to those skilled in the art from the present descriptionconsidered in conjunction with the accompanying drawings whereinpresently preferred embodiments of the invention are illustrated by wayof example. It is to be expressly understood, however, that the drawingsand the associated accompanying portions of this specification areprovided for purposes of illustration and description only, and are notintended as limitations on the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a graphical plot illustrating the flow of the silicone polymercomposition over time upon and in fabrics both pretreated and untreatedwith water repellent chemicals, such as fluorochemicals;

FIG. 2 is a plan view of a prior art silicone polymer treated fabricmagnified 150 times;

FIG. 3a is a photomicrograph of a fabric of the invention magnified 120times;

FIG. 3b is a cross section of a fiber bundle fabric of FIG. 3a magnified600 times;

FIG. 3c is a view of the side of the fabric of FIG. 3a that is theopposite of the side to which silicone polymer was applied;

FIGS. 4a and 4b illustrate diagrammatically one embodiment of anapparatus suitable for use in the practice of the present invention;

FIG. 5 is a diagrammatic representation illustrating the process inaccordance with the present invention;

FIG. 6 illustrates diagrammatically another embodiment of an apparatussuitable for use in the practice of the present invention;

FIG. 7 illustrates diagrammatically another embodiment of an apparatussuitable for use in the practice of the present invention;

FIGS. 8a through 8d are graphs illustrating ways of plotting rheologicalbehavior;

FIG. 9 is a schematic vector diagram illustrating surface tensionforces;

FIG. 10 is a graph relating contact angle over a smooth, solid surface;

FIGS. 11a through 11d show representative velocity profiles;

FIGS. 12a through 12c illustrate diagrammatically another and presentlypreferred embodiment of apparatus suitable for use in the practice ofthe present invention; and

FIGS. 13a through 13c are scanning electron microscope photomicrographsof another representative fabric of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Flexible porous webs usable in the practice of this invention can beclassified into two general types:

(A) Fibrous webs; and

(B) Substrates having open cells or pores.

A porous, flexible fibrous web is comprised of a plurality of associatedor interengaged fibers having interstices defined therebetween.Preferred fibrous webs are (woven or non-woven) fabrics.

Other substrates are comprised of a matrix having open cells or porestherein such as foams or synthetic leathers.

The term "fiber" as used herein refers to a long, pliable, cohesive,natural or man-made (synthetic) thread-like object, such as amonofilament, staple, filament, or the like. A fiber usable in thisinvention preferably has a length at least 100 times its diameter orwidth. Fibers can be regarded as being in the form of units which can beformed by known techniques into yarns or the like. Fibers can be formedby known techniques into woven or non-woven webs (especially fabrics)including weaving, knitting, braiding, felting, twisting, matting,needling, pressing, and the like. Preferably, fibers, such as those usedfor spinning, as into a yarn, or the like, have a length of at leastabout 5 millimeters. Fibers such as those derived from cellulosics ofthe type produced in paper manufacture can be used in combination withlonger fibers as above indicated, as those skilled in the art willreadily appreciate.

The term "filament" as used herein refers a fiber of indefinite length.

The term "yarn" as used herein refers to a continuous strand comprisedof a multiplicity of fibers, filaments, or the like in a bundled form,such as may be suitable for knitting, weaving or otherwise used to forma fabric Yarn occurs as a number of fibers that are twisted together(spun yarn) or a number of filaments that are laid together withouttwist (a zero-twist yarn).

A flexible porous web used as a starting material in this invention isgenerally and typically, essentially planar or flat and has generallyopposed, parallel facing surfaces. Such a web is a three dimensionalstructure comprised of a plurality of fibers with intersticestherebetween or a matrix having open cells or pores therein. The matrixcan be comprised of polymeric solids including fibrous and non-fibrouselements.

The term "web" as used herein is intended to include fabrics and refersto a sheet-like structure (woven or non-woven) comprised of fibersIncluded with the fibers can be non-fibrous elements, such asparticulate fillers, binders, dyes, sizes and the like in amounts thatdo not substantially affect the porosity or flexibility of the web.While preferably, at least 50 weight percent of a web used in thepractice of the present invention is fibers, more preferred webs have atleast about 85 weight percent of their structure as fiber. It ispresently preferred that webs be untreated with any sizing agent,coating, or the like, except as taught herein. The web may comprise alaminated fabric and a non-woven porous substrate.

Non-fibrous elements, such as particulate fillers, binders, dyes, sizesand the like can be added to fibers in a web. Preferred webs have atleast about 85% of their structure comprised of fibrous or fibermaterials and are untreated with any sizing agent, coating, or the like.

Two principal classes of substrates having open pores or cells may beutilized in the present invention: leathers (including natural leathers,and man-made or synthetic leathers), and foamed plastic sheets (orfilms) having open cells.

Foamed plastic sheet or film substrates are produced either bycompounding a foaming agent additive with resin or by injecting air or avolatile fluid into the still liquid polymer while it is being processedinto a sheet or film. A foamed substrate has an internal structurecharacterized by a network of gas spaces, or cells, that make suchfoamed substrate less dense than the solid polymer. The foamed sheets orfilm substrates used as starting materials in the practice of thisinvention are flexible, open-celled structures.

The class of foamed substrate structures known as "structural foams" arenot suitable for use in the practice of this invention since suchstructures involve a solid skin which is believed to be substantiallynon-porous that is integral with and overlies a cellular core.

Natural leathers suitable for use in this invention are typically splithides.

Synthetic leathers have wide variations in composition (or structure)and properties, but they look like leather in the goods in which theyare used. For purposes of technological description, synthetic leatherscan be divided into two general categories: coated fabrics andporomerics.

Synthetic leathers which are poromerics are manufactured so as toresemble leather closely in breathability and moisture vaporpermeability, as well as in workability, machinability, and otherproperties. The barrier and permeability properties normally areobtained by manufacturing a controlled microporous (open celled)structure.

Synthetic leathers which are coated fabrics, like poromerics, have abalance of physical properties and economic considerations. Usually thecoating is either vinyl or urethane. Vinyl coatings can be either solidor expanded vinyl which has internal air bubbles which are usually aclosed-cell type of foam. Because such structures usually have anon-porous exterior or front surface or face, such structures displaypoor breathability and moisture vapor transmission. However, since theinterior or back surface or face is porous, such a coated fabric can beused in the practice of this invention by applying the impregnantsilicone polymer to the back fact.

The fibers utilized in a porous flexible web employed in the practice ofthe present invention can be of natural or synthetic origin. Mixtures ofnatural fibers and synthetic fibers can also be used. Examples ofnatural fibers include cotton, wool, silk, jute, linen, and the like.Examples of synthetic fibers include rayon, acetate, polyesters(including polyethyleneterephthalate), polyamides (including nylon),acrylics, olefins, aramids, azlons, glasses, modacrylics, novoloids,nytrils, rayons, sarans, spandex, vinal, vinyon, and the like.

The term "impregnation", or "impregnate", as used herein, refers toforcing a liquid substance into a porous solid, such as a flexible webor substrate.

With respect to the fluorochemical liquid dispersions (or solutions)used for web pretreatment, the term "impregnation" refers to thepenetration of such dispersions into a porous web, and to thedistribution of such dispersions in a preferably, substantially uniformand controlled manner in such web, particularly as regards the surfaceportions of the individual web component structural elements and fibers.

With respect to the silicone polymer compositions used in thisinvention, the term "impregnation" refers to the penetration of suchpolymeric composition into a porous web, to the distribution of suchcomposition in a controlled manner through such web, and to theresultant, at least partial envelopment of at least a portion of thefibers of such web by such composition in accordance with the presentinvention.

The term "coating" as used herein, refers to a generally continuous filmor layer formed by a material over or on a surface.

The term "internally coated" as used herein, refers to the forming of afilm or layer coated within a porous solid in a specified region, suchas a planar region extending interiorly through a porous web orsubstrate in spaced, parallel relationship to a surface thereof. Suchfilm or layer envelopes, and/or surrounds, and/or impregnates individualfibers or lines cell or pore walls of the porous web or substrate in thespecified region.

The term "envelope" as used herein, refers to the partial or completesurrounding, encasement, or enclosing by a discrete layer, film,coating, or the like, of exposed surface portions of at least someindividual fiber or lining of a cell or pore wall of a porous web. Sucha layer can sometimes be contiguous or integral with other portions ofthe same enveloping material which becomes deposited on internal areasof a web which are adjacent to such enveloping layer, enveloped fiber,lined cell or pore wall, or the like.

The term "elastomeric" as used herein refers to the ability of a curedsilicone polymer impregnated web to stretch and return to its originalstate.

A characteristic of a silicone polymer composition, or impregnant, thatis used for impregnation into a web or substrate in accordance with theteachings of this invention is that apparently only a minimum quantityof the impregnant appears actually to enter into the fibers, cells orpores comprising such web or substrate. The exact amount of impregnantwhich enters into individual fibers, cells or pores is unknown, but isnow estimated to be typically below about 10 weight percent of the totalquantity of impregnant applied to a web or substrate, with the remainderof the impregnant appearing to comprise mainly deposits on and aroundfibers, cells or pores of a web.

The term "curing", or "cure", as used herein, refers to a change instate, condition, and/or structure in a material, such as a curablesilicone polymer composition that is usually, but not necessarily,induced by at least one applied variable, such as time, temperature,radiation, presence and quantity in such material of a curing catalystor curing accelerator, or the like. In the occurrence of curing in anycase, such as the curing of such a polymer composition that has beenimpregnated into a porous flexible substrate or web, the components ofsuch a composition may experience occurrence of one or more of completeor partial (a) polymerization, (b) cross-linking, or (c) other reaction,depending upon the nature of the composition being cured, applicationvariables, and presumably other factors.

The term "filled" as used herein in relation to interstices or opencells, and to the amount of silicone polymer composition therein in agiven web or substrate, designates the presence of such compositiontherein. When a given interstice or open cell is totally taken up bysuch composition, it is "completely filled" or "plugged".

Measurements of the degree of envelopment, interstice fillage, plugging,or the like in an internal coating are conveniently made by microscopy,or preferably by conventional scanning electron microscopy (SEM)techniques. Because of the nature of such measuring by SEM for purposesof the present invention, "a completely filled" interstice or open cellcan be regarded as a "plugged" interstice or open cell.

A flexible, porous fibrous web is preferably untreated or scoured beforebeing treated in accordance with the present invention. Preferably a webis preliminarily treated, preferably saturated, for example, by padding,to substantially uniformly impregnate the web with a fluorochemical.Typically, and preferably, the treating composition comprises adispersion of fluorochemical in a liquid carrier. The liquid carrier ispreferably aqueous and can be driven off with heat after application.The treating composition has a low viscosity, typically comparable tothe viscosity of water or less. After such a treatment, it is presentlypreferred that the resulting treated web exhibits a contact angle withwater measured on an outer surface of the treated web that is greaterthan about 90 degrees. The treated web preferably containsfluorochemical substantially uniformly distributed therethrough. Thus,the fluorochemical is believed to be located primarily on and in theindividual fibers, cells or pores with the web interstices or open cellsbeing substantially free of fluorochemical.

A presently preferred concentration of fluorochemical in a treatmentcomposition is typically in the range of about 1 to about 10%fluorochemical by weight of the total treating composition weight, andmore preferably is about 2.5% of an aqueous treating dispersion. Webweight add-ons of the fluorochemical can vary depending upon suchfactors as the particular web treated, the silicone polymer impregnantto be utilized in the next step of the treatment process of thisinvention, the ultimate intended use and properties of the treated webof this invention, and the like. The fluorochemical weight add-on istypically in the range of about 0.01 to about 5% of the weight of theuntreated web. After fluorochemical impregnation, the web is preferablysqueezed to remove excess fluorochemical composition after which the webis heated or otherwise dried to evaporate carrier liquid and therebyalso accomplish fluorochemical insolubilization or sintering, ifpermitted or possible with the particular composition used.

The fluorochemical treated web is thereafter impregnated under pressureby the procedures taught by this invention, with a predetermined amountof a curable silicone polymer impregnant composition to form a web whosefibers, cells or pores are at least partially enveloped or lined withthe curable silicone polymer impregnant, whose web outer surfaces aresubstantially free of the curable impregnant, whose web interstices oropen cells are not completely filled with the curable impregnant andwhich contains an internal layer of silicone polymer. The curableimpregnant composition utilized preferably exhibits a viscosity greaterthan 1,000 centipoise and less than 2,000,000 centipoise at rest at 25°C. at a shear rate of 10 reciprocal seconds.

The silicone polymer impregnant composition can include conventionaladditives.

The fluorochemical residue that remains after fiber treatment may not beexactly evenly distributed throughout the web, but may be present in theweb in certain discontinuities. For example, these discontinuities maybe randomly distributed small areas upon an individual fiber's surface.However, the quantity and distribution of fluorochemical through a webis believed to be largely controllable. Some portions of thefluorochemical may become dislodged from the web and migrate through thesilicone polymer due to the forces incurred by cause the shear thinningof the silicone polymer.

The curable silicone impregnant composition is believed to be typicallypolymeric, to be usually a mixture of co-curable polymers and oligomers,and to include a catalyst to promote the cure.

The silicone polymer impregnant composition can include, as additivecomponents, polyurethanes, fluorosilicones, silicone-modifiedpolyurethanes, acrylics, polytetrafluoroethylene-containing materials,and the like.

The web is thereafter cured to convert the curable composition into asolid elastomeric polymer.

It is to be understood that the depth of silicone polymer impregnationinto a web can be controlled by the application procedures hereindescribed to provide a selective placement of the silicone polymerimpregnant within the substrate or web. This allows the shear thinning,i.e., viscosity reduction, action to take place throughout the web.

The silicone polymer composition is theorized to be caused to flow anddistribute itself over fibers, cells or pores in a web under theinfluence of the processing conditions provided by this invention. Thisflow and distribution is further theorized to be facilitated andpromoted by the presence of a fluorochemical which has beenpreliminarily impregnated into a web, as taught herein The amount offluorochemical or fluorochemical residue in a web is believed toinfluence the amount, and the locations, where the liquid siliconepolymer impregnant will collect and deposit, and produce an internalcoating in the web. However, there is no intent to be bound herein bytheory.

Some portion of the residue of fluorochemical resulting from apreliminary web saturating operation is theorized to be present upon atreated fiber's surfaces after envelopment of fibers, cells or pores bythe silicone polymer has been achieved during internal web coating bythe practice of this invention. This is believed to be demonstrated bythe fact that a web of this invention still exhibits an enhanced waterand oil repellency, such as is typical of fluorochemicals in porouswebs. It is therefore believed that the fluorochemicals are affectingthe adherence of the silicone polymer as a thin film enveloping layerabout the treated fibers, cells or pores as well as facilitating liquidsilicone polymer impregnant pressurized flow within and about theinterstices or open cells of the web being treated so that the siliconecan assume its position enveloping the fibers or lining the cells orpores of the substrate.

The exact interrelationship between the silicone polymer film and theimpregnated fluorochemical is presently difficult, or perhapsimpossible, to quantify because of the variables involved and becausetransparent silicone polymer is difficult to observe by opticalmicroscopy. It can be theorized that perhaps the silicone polymer andthe fluorochemical each tend to produce discontinuous films upon fibersurface, and that such films are discontinuous in a complementarymanner. It may alternatively be theorized that perhaps the siliconepolymer film is contiguous, or substantially so, relative tofluorochemical molecules on a fiber surface, and that the layer ofsilicone polymer on a fiber surface is so thin that any dislodgement ofthe fluorochemical may release the fluorochemical into the siliconepolymer film thereby allowing the fluorine to orient with the requiredcure temperature of the silicone, reactivating the water surface contactangle so that the water repellant properties of an underlyingfluorochemical are exertable through the silicone polymer film. However,regardless of physical or chemical explanation, the combination ofsilicone polymer film and fluorochemical results in a fiber envelopmentor cell or pore wall lining and the formation of an internal layer ofsilicone polymer in a web when this invention is practiced. Aftercuring, the silicone polymer is permanently fixed material.

By using the impregnation method provided by this invention, one canachieve an impregnation of a silicone polymer composition into a poroussubstrate or web to obtain a desired treated web.

A curable silicone polymer such as used in the practice of thisinvention is applied under pressure using shear forces onto and into aweb or substrate. The shear forces cause the curable silicone polymer toflow into the web. The extent of fiber envelopment and cell or pore walllining is believed to be regulatable by controlling such factors as theselection and applied amount of fluorochemical and curable siliconepolymer in combination with the applied compressive and shear forcesemployed at a given temperature so that fiber envelopment is achievedwhile the interstices and/or open cells of the web are not completelyfilled with such polymer in the region of the internal coating, and theouter opposed surfaces of the web are substantially completely free ofsilicone polymer coating or residue. After such an impregnationprocedure, the curable silicone impregnant is then cured.

The curable silicone polymer impregnant is applied in an amount at leastsufficient to partially saturate the web and fill some of theinterstices or open cells of the web. Then, the web, while tensioned, ispassed over and against shearing means or through a compression zone,such as between rollers or against a shear knife. Thus transverselyapplied shear force and compressive pressure is applied to the web. Thecombination of tensioning, shearing forces, and web traveling speed issufficient to cause the curable silicone polymer impregnant to move intothe web, out from the interstices or open cells around the web fibers,cells or pores being enveloped, thereby leaving at least some of theinterstices and/or open cells unfilled in regions of the web outside ofthe region occupied by the interior coating, and preferablysubstantially free of, silicone polymer impregnant. Excess siliconepolymer is removed by the surface wiping action of the shearing means.The curable silicone polymer impregnant enveloping the fibers isthereafter cured.

The desired impregnation or penetration of, and distribution of siliconepolymer in, a web is believed to be achieved by localized pressuringforces exerted on a web surface which are sufficiently high to cause theviscosity of a silicone polymer impregnant composition to be locallyreduced, thereby permitting such silicone impregnant to flow under suchpressuring and to impregnate the web and to envelope its fibers or linethe cell or pore walls thereof. To aid in this process, the web ispreferably at least slightly distorted by tensioning or stretching,while being somewhat transversely compressed at the location of theimpregnation. This distortion is believed to facilitate the entrance ofthe silicone polymer composition into the web. When the compression andtension are released, the silicone polymer composition is believed to besqueezed or compressed within and through the interstitial spaces, oropen cell spaces, of the treated web.

If, for example, too much silicone polymer is present in the finishedproduct, then either or both the tension and shear force can beincreased, and vice versa for too little silicone polymer. If flow isnot adequate upon the fibers, producing incomplete fiber envelopment,then the viscosity of the silicone impregnant composition can be reducedby reducing the pressures and temperatures employed for theimpregnation. Alternatively, if the viscosity is excessive, then theimpregnating pressure and/or temperature can be increased. Oppositeadjustments should be made if silicone polymer impregnant flow isinsufficiently viscous. If the silicone polymer impregnating compositionis resistant to being positioned in a desired location in a desiredamount in a given web at various viscosities and/or pressures, then thelevel of fluorochemical pretreatment of the web can be increased, as inthe case of overimpregnation, or decreased, as in the case ofunderimpregnation.

In one embodiment of an impregnation procedure, the pressuredimpregnation of a web occurs between two rollers. One such roller bearsa silicone polymer impregnant, typically and preferably distributeduniformly upon and over a circumferentially extending textured, orgravure surface. Such roller rotates (i) in the same direction as afacing roller and (ii) oppositely to the direction of movement of acontinuously moving web traveling past the localized impregnation areaachieved between such roller and such moving web. The unidirectionalrotation of the two rollers is believed to produce a distorting andstretching force or effect upon the web. This force is believed topromote penetration of the silicone polymer impregnant into the web.This form of impregnant application or coating can be termed "reverseroll coating" for convenience. Preferably, the reverse coating rollershave generally horizontal axes while the moving web moves generallyhorizontally. The web is further concurrently both longitudinallytensioned and distorted by being stretched against metering bars, barknives, and the like which are urged against the web.

Such an initial pressured impregnation step is preferably followed by aseries of further pressured web treatment steps believed to accomplishimpregnant reintroduction, impregnant distribution, impregnant scraping,and excess impregnant removal and recovery. The collective result ofsuch steps gradually produces a web wherein the silicone polymerimpregnant envelopes to a desired extent the fibers or lines the cell orpore walls comprising the web and collects within a desired internalregion or zone in the web thereby filling or plugging intersticialspaces, or open cells or pores, of the web in such region, but notfilling the internal structure of the treated web with silicone polymerbeyond a desired extent. Particularly, and for example, in a fabric, asilicone polymer composition may be made to substantially completelyenvelope the fibers or line the cells or pores thereof and fill theinterstitial spaces thereof in such internal region.

In another embodiment of an impregnation procedure, application ofsilicone polymer impregnant to a web occurs from a reservoir. Thisreservoir of silicone impregnant is positioned tightly against thetensioned, moving web (or fabric). The linearly extending, preferablyvertically upwardly moving, web (or fabric), constitutes a wall portionof the reservoir. Next, along the path of web travel, a bar or shearknife is pressed strongly and transversely against and laterally acrossthe longitudinally tensioned web (or fabric). Further along the path ofweb movement, a shear blade or flexible scraper knife is also stronglyand transversely forced laterally across and against the tensioned web.More than one shear knife, or more than one flexible compressive knife,can be successively positioned along the path of web movement. Theseblade means are believed to reintroduce the silicone impregnant into theweb, to distribute the silicone polymer, and to promote and complete theenvelopment of fibers or lining of the cell or pore walls and fillage ofinterstices and open cells with silicone polymer, and form an internalcoating in a desired region in a web. These scraper knives or shearblades are also believed to force the silicone polymer impregnantfurther into the three-dimensional structure of the web. Also, theseknives, particularly the scraper knives, wipe or scrape excess siliconepolymer impregnant off the surface of the web, thereby regulating theamount of silicone polymer impregnated.

The transversely applied shear forces applied across and against the webare sufficiently high to achieve temporarily and locally, a lowering ofthe viscosity of the preferably thixotropic viscous silicone polymerimpregnant. The lowered viscosity silicone polymer impregnant is thusenabled to flow into, and upon, the internal three-dimensional structureof the web. Because the silicone polymer composition that is beingapplied is subject to cure with heat or radiation and time, and becausethe pressured impregnation is believed to produce localized heat, theshearing conditions used prior to curing are preferably controlled tominimize premature curing. The properties of the silicone polymerimpregnant are preferably selected to be such that cure, or excessivecure, does not occur while the web is being treated with siliconepolymer during the pressured impregnation. The cure preferably occursonly after the web impregnation procedure has been completed.Preferably, the cure temperature of the silicone polymer composition isrelatively high (preferably above about 250° F.) and the heat exposuretime is such as is needed to obtain a desired solid resilientelastomeric silicone polymer.

If desired, the rheology of the silicone polymer impregnant may bealtered or controlled. Characteristics of a web are believed to beinfluenced by rheology, but it is believed that, in general, thisinvention can be practiced without careful control of rheology whilecontrolling viscosity.

The viscosity of the silicone polymer impregnant is preferably loweredby the high pressure (shear) forces exerted during impregnation.However, such a pressure- and/or temperature-induced lowered viscosityshould not go down too low, otherwise the impregnant can flowsubstantially uncontrolled in the web in the manner of a low viscosityliquid that is saturated and impregnated into a web as in prior art webtreatments If the viscosity of the silicone polymer composition is toolow at the time of impregnation, then the web interstices or open cellscan become excessively filled therewith, and the impregnant is not, forexample, reliably and controllably applied to achieve an envelopment ofthe structural elements (including fibers) of the web being treatedtogether with internal coating formation.

Benzophenones, and particularly 2,4-dihydroxybenzophenone, are believedto be a particularly useful class of additives to the starting siliconepolymer composition, as hereinbelow described.

As above indicated, the activity transpiring at a final step in thepractice of a method of this invention is generically referred to hereinas curing. Conventional curing conditions known to the prior art forcuring silicone polymer compositions are generally suitable for use inthe practice of this invention. Thus, temperatures in the range of about250° F. to about 350° F. are used and times in the range of about 30seconds to about 1 minute can be used, although longer and shortercuring times and temperatures may be used, if desired, when thermalcuring is practiced. Radiation curing, as with an electron beam orultraviolet light can also be used. However, using platinum catalysts toaccelerate the cure while using lower temperatures and shorter curetimes is preferable.

Because either filled plugged or almost filled interstices or open cellsin the region of an internal coating remain transmissive of air in curedwebs of this invention, the webs are characteristically air permeable orbreathable.

Sample webs or fabrics that are beneficially impregnated, fiberenveloped and internally coated in accordance with the invention arebelieved to include nylon, cotton, rayon and acrylic fabrics, as well asfabrics that are blends of fiber types. Sample nylon fabrics includelime ice, hot coral, raspberry pulp, and diva blue Tactel® (registeredtrademark of ICI Americas, Inc.) fabrics available from agent ArthurKahn, Inc. Sample cotton fabrics include Intrepid® cotton cornsilk,sagebrush cotton, and light blue cotton fabrics available also fromArthur Kahn, Inc. Non-woven, mono-filamentous, fabrics such as TYVEK®(registered trademark of E.I. duPont de Nemours Co., Inc.) and the likeare also employable.

As indicated above, a web is preferably pretreated and impregnated witha fluorochemical prior to being impregnated under pressure with asilicone polymer composition as taught herein.

The fluorochemical impregnation is preferably accomplished by firstsaturating a web with a liquid composition which incorporates thefluorochemical, and then, thereafter, removing the excess liquidcomposition and residual carrier fluid by draining, compression, drying,or some combination thereof from the treated web.

It is now believed that any fluorochemical known in the art for use inweb, particularly fabric treatment in order to achieve water repellency,soil repellency, grease repellency, or the like, can be used forpurposes of practicing the present invention.

It is believed that a typical fluorochemical of the type used for webtreatment can be characterized as a compound having one or more highlyfluorinated portions, each portion being a fluoroaliphatic radical orthe like, that is (or are) functionally associated with at least onegenerally non-fluorinated organic portion. Such organic portion can bepart of a polymer, part of a reactive monomer, a moiety with a reactablesite adapted to react with a binder, or the like.

Such a compound is typically applied to a fabric or other web as asuspension or solution in either aqueous or non-aqueous media. Suchapplication may be conventionally carried out in combination with anon-fluorine or fluorine containing resin or binder material for thepurpose of providing improved durability as regards such factors aslaundering, dry cleaning, and the like.

Fluorochemicals are sometimes known in the art as durable waterrepellant (DWR) chemicals, although such materials are typicallybelieved to be not particularly durable and to have a tendency to washout from a fabric treated therewith. In contrast, fiber enveloped websof this invention which have been pretreated with a fluorochemicaldisplay excellent durability and washability characteristics. Indeed,the combination of fluorochemical pretreatment and silicone polymerfiber envelopment such as provided by the present invention appears toprovide synergistic property enhancement because the effects orproperties obtained appear to be better than can be obtained than byusing either the fluorochemical or the silicone polymer alone for webtreatment.

Exemplary water repellant fluorochemical compositions include thecompositions sold under the name Milease® by ICI Americas Inc. with thetype designations F-14N, F-34, F-31X, F-53. Those compositions with the"F" prefix indicate that they contain a fluorochemical as the principalactive ingredient. More particularly, Milease® F-14 fluorochemical, forexample, is said to contain approximately 18 percent perfluoroacrylatecopolymer, 10 acetone (CAS 67-64-1) dispersed and dissolved in 65percent water. Milease® F-31X is said to be a dispersion of acombination of fluorinated resin, acetone, and water.

Still another suitable class of water repellant chemicals is thePhobotex® chemicals of Ciba/Geigy identified as Phototex® FC104, FC461,FC731, FC208 and FC232 which are each believed to be suitable for use,typically in approximately a 5 percent concentration, in saturating aweb for use in the invention. These and many other water repellentfluorochemicals are believed to be capable of creating a surface contactangle with water of greater than about 90 degrees when saturated into aweb and to be suitable for use in the practice of this invention.

Another group of useful water repellent fluorochemicals is theTEFLON®-based soil and stain repellents of E.I. duPont de Nemours & Co.Inc., 1007 Market Street, Wilmington, Del. 19898. Suitable TEFLON® typesfor use in the practice of this invention include TEFLON® G, NPA, SKF,UP, UPH, PPR, N, and MLV. The active water repellent chemical of eachcomposition is believed to be a fluorochemical in polymeric form that issuitable for dispersion in water, particularly in combination with acationic surfactant as a dispersant. These dispersions are dilutable inall proportions with water at room temperature. One preferred class offluorochemical treating compositions useful in the practice of thisinvention comprises about 1 to about 10 weight percent, more preferablyabout 5 weight percent of one of the above indicated TEFLON®-type waterrepellent fluorochemcials in water.

Another major group of suitable water repellent fluorochemicalcompositions useful in the practice of the invention is commerciallyavailable under the designation ZEPEL® rain and stain repellentchemicals of E.I. duPont de Nemours & Co. Inc., such as ZEPEL® waterrepellent chemicals types B, D, K, RN, RC, OR, HT, 6700 and 7040. Eachis believed to be a fluorochemical in polymeric form that is dispersiblein all proportions at room temperature. The dispersants ZEPEL® B, D, K,and RN are believed to be cationic, while the dispersant ZEPEL® RC isbelieved to be non-ionic.

As an exemplary composition, ZEPEL® 6700 is said to be comprised of 15to 20 percent perfluoroalklyl acrylic copolymer, 1 to 2 percentalkoxylated carboxylic acid, and 3 to 5 percent ethylene glycol.Exemplary characteristics of the composition include a boiling point of100° C. at 760 mm Hg and a specific gravity of 1.08. The volatiles areapproximately 80 percent by weight. The pH is 2 to 5. The odor is mild;the concentrate form is that of a semi-opaque liquid; and theconcentrate color is straw white. The composition and characteristics ofZEPEL® 7040 repellent chemical are believed to be substantiallyidentical to those of ZEPEL®6700 except that the former compositionadditionally contains 7 to 8 percent acetone.

Another major group of water repellent fluorochemicals comprises theScotchgard® water repellent chemicals of 3M Co., St. Paul, Minn. TheScotchgard® fluorochemicals are believed to be aqueously dispersedfluorochemicals in polymeric form. The compositions of two suitableScotchgard® water repellent fluorochemicals are believed to be disclosedin U.S. Pat. Nos. 3,393,186 and 3,356,628, which patents areincorporated herein by reference. Thus, the Scotchgard® fluorochemicalof U.S. Pat. No. 3,356,628 consists of copolymers of perfluoroacrylatesand hydroxyalkyl acrylates. These copolymers are suitable for use as anoil and water repellent coating on a fibrous or porous surface. Theyhave a carbon to carbon main chain and contain recurring monovalentperfluorocarbon groups having from 4 to 18 carbon atoms each and alsohaving recurring hydroxyl radicals. From 20 to 70 percent of the weightof such copolymer is contributed by fluorine atoms in theperfluorocarbon groups and from 0.05 to 2 percent of the weight of thecopolymer is contributed by the hydroxyl radicals. Such copolymer issaid to have improved surface adherability properties as compared to thehomopolymer of a corresponding fluorocarbon monomer.

The Scotchgard® fluorochemical of U.S. Pat. No. 3,393,186 consists ofperfluoroalkenylacrylates and polymers thereof. An exemplary fluorinatedmonomer has the formula: ##STR1## wherein R_(f) is a fluorocarbon grouphaving from 3 to 18 carbon atoms, R is hydrogen or methyl, and n is0-16. Such a water repellent fluorochemical composition is supplied andsaturated into the substrate web as a readily pourable aqueousdispersion.

U.S. Pat. No. 4,426,476 discloses a fluorochemical textile treatingcomposition containing a water-insoluble fluoroaliphatic radical, analiphatic chlorine-containing ester and a water insoluble,fluoroaliphatic radical containing polymer.

U.S. Pat. No. 3,896,251 discloses a fluorochemical textile treatingcomposition containing a fluoroaliphatic radical containing linear vinylpolymer having 10 to 60 weight percent fluorine and a solvent solublecarbodiimide preferably comprising fluoroaliphatic groups. A table inthis patent lists a plurality of prior art fluoroaliphatic radicalcontaining polymers useful for the treatment of fabrics and the priorart patents where such polymers are taught.

U.S. Pat. No. 3,328,661 discloses textile treating solutions of acopolymer of an ethylenically unsaturated fluorocarbon monomer and aethylenically unsaturated epoxy group containing monomer.

U.S. Pat. No. 3,398,182 discloses fluorocarbon compounds useful forfabric treatment that contain a highly fluorinated oleophobic andhydrophobic terminal portion and a different non-fluorinated oleophilicportion linked together by a urethane radical.

Water repellent fluorochemical compositions are preferably utilized tosaturate a starting untreated porous web substrate so that suchcomposition and its constituents wet substantially completely andsubstantially uniformly all portions of the web. Such a saturation canbe accomplished by various well known techniques, such as dipping theweb into a bath of the composition, or padding the composition onto andinto the web, or the like. Padding is the presently preferred method offluorochemical application.

After application of the fluorochemical composition to the web, thewater (or liquid carrier) and other volatile components of thecomposition are removed by conventional techniques to provide a treatedweb that contains the impregnated fluorochemical throughout the websubstrate.

In a preferred procedure of fluorochemical impregnation, a web issubstantially completely saturated with an aqueous dispersion of afluorochemical. Thereafter, the resulting impregnated web is compressedto remove excess portions of said dispersion. Finally, the web is heatedto evaporate the carrier liquid. If the fluorochemical is curable, thenthe heating also accomplishes curing.

After the fluorochemical treatment, the fluorochemical is found only onor in the web structural elements or fibers and is substantiallycompletely absent from the web interstices.

The fluorochemical concentration in the treating composition is such asto permit a treated fluorochemical containing web, after volatiles ofthe treating composition are removed, to exhibit a contact angle withwater applied to an outer web surface which is greater than about 90°.More preferably, the contact angle provided is greater than about 130°.

The web weight add-on provided by the fluorochemical after removal ofvolatiles is usually relatively minor. However, the weight add on canvary with such factors as the nature of web treated, the type ofsilicone impregnant utilized in the next step of the process, thetemperature at which the impregnant is applied, the ultimate usecontemplated for a web, and the like.

Typical weight add-ons of fluorochemical are in the range of about 1 toabout 10 percent of the original weight of the web. More preferably,such weight add-ons are about 2 to about 4 weight percent of the weightof the starting fabric.

Durability of a web that has been treated with a fluorochemical anddurability of a web that is subsequently treated with a silicone polymercan sometimes be improved by the conventional process of "sintering".The exact physical and chemical processes that occur during sinteringare unknown. The so-called sintering temperature utilized is a functionof the fluorochemical composition utilized and such temperature isfrequently recommended by fluorochemical manufacturers. Typically,sintering is carried out at a temperature of about 130° to about 160° C.for a period of time of about 2 to about 5 minutes. Acid catalysts canbe added to give improved durability to laundering and dry cleaningsolvents.

The fluorochemical is believed to provide more than water or otherrepellent properties to the resulting treated (impregnated) web,particularly since the curable silicone impregnant is often itself awater repellent. Rather, and without wishing to be bound by theory, itis believed that the fluorochemical in a treated web provides relativelubricity for the treated fibers during the pressure application of thecurable silicone polymer impregnant. The silicone polymer impregnant isapplied under pressures which can be relatively high, and thisimpregnant is itself relatively viscous, as is discussed herein. Inorder for the curable silicone polymer impregnant to coat and envelopeweb fibers, but not fill web interstitial voids, the fibers of the webmay move over and against each other to a limited extent, thereby topermit entry of the silicone impregnant into and around the fibers. Itis thought that the fluorochemical deposits may facilitate such fibermotion and facilitate envelopment during the pressure impregnation andsubsequent shearing processing.

Alternatively, the fluorochemical may inhibit deposition of the siliconepolymer impregnant at the positions of the fluorochemical deposits whichsomehow ultimately tends to cause thin enveloping layers of siliconepolymer to form on fibers.

The precise physics and chemistry of the interaction between thefluorochemical and the silicone impregnant is not understood. A simpleexperiment demonstrates movement of the liquid silicone polymer asinfluenced by the presence of the fluorochemical:

A piece of fabric, for example the Red Kap Milliken poplin polyestercotton blend fabric, is cut into swatches. One swatch is treated with anadjuvant, for example a three percent solution of the durablewater-repellent chemical Milease® F-31X. The treated swatch and anuntreated swatch are each positioned at a 45° angle to plumb. A measuredamount, for example one-half ounce, of a viscous polymer composition,for example the Mobay® 2530A/B silicon composition, is dropped onto theinclined surface of each swatch. The distance in centimeters that thecomposition flows downwards upon the surface of the swatch is measuredover time, typically for 30 minutes.

A graphical plot of the flow of the silicone composition respectivelyupon the untreated and treated swatches over time can be prepared, suchas shown in FIG. 1. At the expiration of 30 minutes the viscouscomposition has typically traveled a distance of about 8.8 centimetersupon the treated swatch, or a rate of about 0.29 centimeters per minute.At the expiration of the same 30 minutes, the viscous composition hastypically traveled a lesser distance of about 7.1 centimeters upon theuntreated swatch, or a rate of about 0.24 centimeters per minute.Qualitatively commensurate results are obtainable with other DWRfluorochemical adjuvants that facilitate the viscous flow of polymercompositions in accordance with the invention. Indeed, if desired, thesimple flow rate test can be used to qualify an adjuvant compound forits employment within the method of the invention. The fluorochemicalpretreated web generally increases the surface contact angle of thesilicone polymer while reducing the amount of saturation of the siliconepolymer into the fibers themselves.

The fluorochemical treated web is thereafter impregnated under pressurewith a predetermined amount of a curable silicone polymer impregnantcomposition to form a web whose fibers are preferably substantiallycompletely enveloped with such curable impregnant and whose outersurfaces and interstices are preferably substantially completely free ofthe curable impregnant. The silicone polymer impregnant is thereaftercured by heat, radiation, or the like. Even room temperature curing canbe used. A silicone polymer impregnated, fluorochemical pretreated webcan be interveningly stored before being subjected to curing conditionsdepending upon the so-called pot life of the treating silicone polymerimpregnant.

A curable silicone polymer impregnant composition utilized in thepractice of this invention preferably has a viscosity that is sufficientto achieve an internal coating of the web. Generally, the viscosity isgreater than about 1000 centipoise and less than about 2,000,000centipoise at a shear rate of 10 reciprocal seconds. It is presentlymost preferred that such composition have a viscosity in the range ofabout 5,000 to about 10,000 centipoise at 25° C. Such a composition isbelieved to contain less than about 1% by weight of volatile material.

The silicone polymer is believed to be typically polymeric and to becommonly a mixture of co-curable polymers, oligomers, and/or monomers. Acatalyst is usually also present, and, for the presently preferredsilicone polymer compositions discussed hereinafter, is platinum or aplatinum compound, such as a platinum salt.

A preferred class of liquid curable silicone polymer compositionscomprises a curable mixture of the following components:

(A) at least one organo-hydrosilane polymer (including copolymers);

(B) at least one vinyl substituted polysiloxane (including copolymers);

(C) a platinum or platinum containing catalyst; and

(D) (optionally) fillers and additives.

Typical silicone hydrides (component A) are polymethylhydrosiloxaneswhich are dimethyl siloxane copolymers. Typical vinyl terminatedsiloxanes are vinyldimethyl terminated or vinyl substitutedpolydimethylsiloxanes. Typical catalyst systems include solutions orcomplexes of chloroplatinic acid in alcohols, ethers, divinylsiloxanes,and cyclic vinyl siloxanes.

The polymethylhydrosiloxanes (component A) are used in the form of theirdimethyl copolymers because their reactivity is more controllable thanthat of the homopolymers and because they result in tougher polymerswith a lower cross-link density. Although the reaction with vinylfunctional silicones (component B) does reportedly take place in 1:1stoichiometry, the minimum ratio of hydride (component A) to vinyl(component B) in commercial products is reportedly about 2:1 and may beas high as 6:1. While the hydrosilation reaction ofpolymethylhydrosilane is used in both so called RTV (room temperaturevulcanizable) and LTV (low temperature vulcanizable) systems, and whileboth such systems are believed to be useful in the practice of thepresent invention, systems which undergo curing at elevated temperatureare presently preferred.

Elastomers produced from such a curing reaction are known to demonstratetoughness, tensile strength, and dimensional stability.

Particulate fillers are known to be useful additives for incorporationinto liquid silicone polymer compositions. Such fillers apparently notonly can extend and reinforce the cured compositions produced therefrom,but also can favorably influence thixotropic behavior in suchcompositions. Thixotropic behavior is presently preferred incompositions used in the practice of this invention. A terminal silanol(Si--OH) group makes such silanol siloxanes susceptible to reaction incuring, as is believed desirable.

It is believed that all or a part of component B can be replaced with aso called silanol vinyl terminated polysiloxane while using an organotincompound as a suitable curing catalyst as is disclosed in U.S. Pat. No.4,162,356. However, it is presently preferred to use vinyl substitutedpolysiloxanes in component B.

A silicone composition useful in this invention can contain curablesilicone resin, curable polyurethane, curable fluorosilicone, curablemodified polyurethane silicones, curable modified siliconepolyurethanes, curable acrylics, polytetrafluoroethylene, and the like.

One particular type of silicone impregnant composition which is believedto be well suited for use in the impregnation step of the method of theinvention is taught in U.S. Pat. Nos. 4,472,470 and 4,500,584 and inU.S. Pat. No. 4,666,765. The contents of these patents are incorporatedherein by reference. Such a composition comprises in combination:

(i) a liquid vinyl chainterminated polysiloxane having the formula,##STR2## wherein R and R¹ are monovalent hydrocarbon radicals free ofaliphatic unsaturation with at least 50 mole percent of the R¹ groupsbeing methyl, and where n has a value sufficient to provide a viscosityof about 500 centipoise to about 2,000,000 centipoise at 25° C.;

(ii) a resinous organopolysiloxane copolymer comprising:

(i) (R²)₃ SiO₀.5 units and SiO₂ units, or

(ii) (R³)₂ SiO₀.5 units, (R³)₂ SiO units and SiO₂ units, or

(iii) mixtures thereof, where R² and R³ are selected from the groupconsisting of vinyl radicals and monovalent hydrocarbon radicals free ofaliphatic unsaturation, where from about 1.5 to about 10 mole percent ofthe silicon atoms contain silicon-bonded vinyl groups, where the ratioof monofunctional units to tetrafunctional units is from about 0.5:1 toabout 1:1, and the ratios of difunctional units to tetrafunctional unitsranges up to about 0.1:1;

(iii) a platinum or platinum containing catalyst; and

(iv) a liquid organohydrogen-polysiloxane having the formula: ##EQU1##in an amount sufficient to provide from about 0.5 to about 1.0silicon-bonded hydrogen atoms per silicon-bonded vinyl group of abovecomponent (i) or above subcomponent (iii) of, R_(a) is a monovalenthydrocarbon radical free of aliphatic unsaturation, a has a value offrom about 1.0 to about 2.1, b has a value of from about 0.1 to about1.0, and the sum of a and b is from about 2.0 to about 2.7, there beingat least two silicon-bonded hydrogen atoms per molecule.

Optionally, such a composition can contain a finely divided inorganicfiller (identified herein for convenience as component (v)).

For example, such a composition can comprise on a parts by weight basis:

(a) 100 parts of above component (i);

(b) 100-200 parts of above component (ii);

(c) a catalytically effective amount of above component (iii), which,for present illustration purposes, can range from about 0.01 to about 3parts of component (iii), although larger and smaller amounts can beemployed without departing from operability (composition curability) asthose skilled in the art will appreciate;

(d) 50-100 parts of above component (iv), although larger and smalleramounts can be employed without departing from operability (curability)as those skilled in the art will appreciate; and

(e) 0-50 parts of above component (v).

Embodiments of such starting composition are believed to be availablecommercially from various manufacturers under various trademarks andtrade names.

As commercially available, such a composition is commonly in thetwo-package form (which are combined before use). Typically, thecomponent (iv) above is maintained apart from the components (i) and(ii) to prevent possible gelation in storage before use, as thoseskilled in the art appreciate. For example, one package can comprisecomponents (i) and (ii) which can be formulated together with at leastsome of component (ii) being dissolved in the component (i), along withcomponent (iii) and some or all of component (v) (if employed), whilethe second package can comprise component (iv) and optionally a portionof component (v) (if employed). By adjusting the amount of component (i)and filler component (v) (if used) in the second package, the quantityof catalyst component (iii) required to produce a desired curablecomposition is achieved. Preferably, component (iii) and the component(iv) are not included together in the same package. As is taught, forexample, in U.S. Pat. No. 3,436,366 (which is incorporated herein byreference), the distribution of the components between the two packagesis preferably such that from about 0.1 to 1 part by weight of the secondpackage is employed per part of the first package. For use, the twopackages are merely mixed together in suitable fashion at the point ofuse.

Other suitable silicone polymer compositions are disclosed in thefollowing U.S. patents:

U.S. Pat. No. 4,032,502 provide compositions containing a linearpolydiorganosiloxane having two siloxane bonded vinyl groups permolecule, organosiloxane that is soluble in such linearpolydiorganosiloxane and comprised of a mixture of a polyorganosiloxaneand a polydiorganosiloxane, platinum-containing catalyst, a platinumcatalyst inhibitor, and a reinforcing silica filler whose surface hasbeen treated with an organosilicone compound.

U.S. Pat. No. 4,108,825 discloses a composition comprising atriorganosiloxy end-blocked polydiorganosiloxane, anorganohydrogensiloxane having an average of at least 2.1 silicon-bondedhydrogen atoms per molecule, a reinforcing silica filler having asurface treated with an organosilicone compound, a platinum catalyst,and ceric hydrate. Such silicone polymer composition is desirable when aweb is being prepared which has flame retardant properties.

U.S. Pat. No. 4,162,243 discloses a silicone composition of 100 parts byweight triorganosiloxy endblocked polydimethylsiloxane, reinforcingamorphous silica that is surface treated with organosiloxane groups,organohydrogensiloxane, and platinum catalyst.

U.S. Pat. No. 4,250,075 discloses a liquid silicone polymer compositionthat comprises vinyldiorganosiloxy endblocked polydiorganosiloxane,polyorganohydrogensiloxane, platinum catalyst, platinum catalystinhibitor, and carbonaceous particles. Such a silicone polymercomposition is useful when a web of this invention is being preparedthat has electrically conductive properties.

U.S. Pat. No. 4,427,801 discloses a curable organopolysiloxane of liquidtriorganosiloxy endblocked polydiorganosiloxane wherein thetriorganosiloxy groups are vinyl dimethylsiloxy orvinylmethylphenylsiloxy, finely divided amorphous silica particlestreated with mixed trimethylsiloxy groups and vinyl-containing siloxygroups, organopolysiloxane resin containing vinyl groups,organohydrogensiloxane, and a platinum containing catalyst.

U.S. Pat. No. 4,500,659 discloses a silicone composition of liquidtriorganosiloxy endblocked polydimethylsiloxane wherein thetriorganosiloxy units are dimethylvinylsiloxy ormethylphenylvinylsiloxy, a reinforcing filler whose surface has beentreated with a liquid hydroxyl end-blocked polyorganosiloxane which isfluorine-substituted, a liquid methylhydrogensiloxane, and aplatinum-containing catalyst.

U.S. Pat. No. 4,585,830 discloses an organosiloxane composition of atriorganosiloxy-endblocked polydiorganosiloxane containing at least twovinyl radicals per molecule, an organohydrogensiloxane containing atleast two silicone-bonded hydrogen atoms per molecule, aplatinum-containing hydrosilation catalyst, optionally a catalystinhibitor, a finely divided silica filler, and a silica treating agentwhich is at least partially immiscible with said polydiorganosiloxane.

U.S. Pat. No. 4,753,978 discloses an organosiloxane composition of afirst diorganovinylsiloxy terminated polydiorganosiloxane exhibiting aspecified viscosity and having no ethylenically unsaturated hydrocarbonradicals bonded to non-terminal silicon atoms, a seconddiorganovinylsiloxy terminated polydiorganosiloxane that is misciblewith the first polydiorganosiloxane and contains a vinyl radical, anorganohydrogensiloxane, a platinum hydrosilation catalyst, and a treatedreinforcing silica filler.

U.S. Pat. No. 4,785,047 discloses silicone elastomers having a mixtureof a liquid polydiorganosiloxane containing at least two vinyl or otherethylenically unsaturated radicals per molecule and a finely dividedsilica filler treated with a hexaorganodisilazane which mixture is thencompounded with additional hexaorganodisiloxane.

U.S. Pat. No. 4,329,274 discloses viscous liquid silicone polymercompositions that are believed to be suitable and which are comprised ofvinyl containing diorganopolysiloxane (corresponding to component B),silicon hydride siloxane (corresponding to component A) and an effectiveamount of a catalyst which is a halogenated tetrameric platinum complex.

U.S. Pat. No. 4,442,060 discloses a mixture of 100 parts by weight of aviscous diorganopolysiloxane oil, 10 to 75 parts by weight of finelydivided reinforcing silica, 1 to 20 parts by weight of a structuringinhibitor, and 0.1 to 4 parts by weight of 2,4-dichlorobenzoyl peroxidecross-linking agent.

Silicone resin compositions shown in Table I below have all been used inthe practice of this invention. Such compositions of Table I arebelieved to involve formulations that are of the type hereinabovecharacterized.

                  TABLE I                                                         ______________________________________                                        Illustrative Starting Silicone Polymer Compositions                                      Trade                                                              Manufacturer                                                                             Designation   Components.sup.(1)                                   ______________________________________                                        Mobay      Silopren ®                                                                              Vinyl-terminated                                                LSR 2530      polydimethyl/siloxane                                                         with fumed silica,                                                            methylhydrogen                                                                polysiloxane                                         Mobay      Silopren ®                                                                LSR 2540/01                                                        Dow Corning                                                                              Silastic ®                                                                              polysiloxane                                                    595 LSR                                                            General    SLE 5100      polysiloxane                                         Electric                                                                      General    SLE 5106      siloxane resin                                       Electric                 solution                                             General    SLE 5300      polysiloxane                                         Electric                                                                      General    SLE 5500      polysiloxane                                         Electric                                                                      Shin-Etsu  KE 1917                                                            Shin-Etsu  DI 1940-30                                                         SWS        Liquid Rubber silicone fluid with                                  Silicones  BC-10         silicone dioxide                                     Corporation              filler and curing                                                             agents                                               ______________________________________                                         Table I footnote: .sup.(1) Identified components do not represent complet     composition of the individual products shown.                            

When a polymer composition of a silicone polymer and a benzophenone isimpregnated into a porous web as taught herein, protection of an organicweb against ultraviolet radiation is improved, and the degradationeffects associated with ultraviolet light exposure are inhibited, as maybe expected from prior art teachings concerning the behavior ofbenzophenones.

Surprisingly and unexpectedly, however, when silicone polymercompositions such as used in this invention contain a benzophenone, theresulting composition is believed to display improved viscositycharacteristics, particularly thixotropic characteristics, and alsocuring acceleration, when such a composition is subjected to high shearforces.

The normal (ambient conditions or rest) viscosity and rheologycharacteristics of a composition useful in the present invention arelowered by high pressure (shear) forces applied thereto, such as theshear forces that occur during pressured impregnation. However, thispressure- and temperature-induced lower viscosity does not reachinoperative harmful levels, such as hereinabove discussed.

A presently preferred benzophenone additive useful in the presentinvention is 2,4-dihydroxygenzophenone.

The regulation of internal and external rheology, and of viscosity,achieved in a characteristically highly viscous polymer composition ofthe invention is believed to be an important and desirable feature ofthe benzophenone and silicone polymer compositions which find use ininternally coated web manufacture as taught herein.

In such compositions useful in the present invention, a control ofcompositional rheology, and particularly of complex viscosity, isaccomplishable, if desired, by the selective addition of diluent andadditives. These polymer compositions characteristically exhibitperformance curves indicating substantially level and constant lossmodulus, storage modulus, and complex viscosity over extendedtemperature ranges. The graphic plots of loss modulus, storage modulus,and complex viscosity versus temperature all are believed tocharacteristically exhibit a sharp knee that shows the moduli toincrease in value rapidly at cure temperatures.

Preferably, the curing proceeds to a point where the silicone polymercomposition is no longer sticky, or tacky, but preferably curing is notallowed to continue to a point where the resulting polymer compositionbecomes excessively hard, rigid, or brittle. Compositions of thisinvention are controllably curable into polymeric materials which arepreferably not sticky or tacky, and which have desirable elastomeric,flexural, and resiliency characteristics.

To prepare a silicone polymer composition which incorporates abenzophenone, one preferably admixes the benzophenone with the siliconepolymer composition at the time of use. The benzophenone component canbe regarded as, or identified herein for convenience as, component (vi).On the same parts by weight basis above used, a composition of thisinvention preferably contains from about 0.3 to about 10 parts of suchcomponent (vi), although larger and smaller amounts can be used, ifdesired, without departing from the spirit and scope of the invention.

One class of derivitized benzophenones useful in the practice of thisinvention is characterized by the generic formula: ##STR3## where: R¹and R² are each selected from the group consisting of hydroxyl, loweralkoxy, and hydrogen, and

n and m are each an integer of 1 or 2

Examples of substituted benzophenones of formula (3) include

                  TABLE II                                                        ______________________________________                                        Substituted Benzophenones                                                                             (Commercially available                               ID                      under specified                                       No.  (Name)             trademark from BASF)                                  ______________________________________                                        1    2,4-dihydroxybenzophenone                                                                        "Uvinul" 400.sup.1                                    2    2-hydroxy-4-methoxy-                                                                             "Uvinul" M-40                                              benzophenone                                                             3    2,2', 4,4'-        "Uvinul" D-50                                              tetrahydroxybenzophenone                                                 4    2,2'-dihydroxy-4,4'-                                                                             "Uvinul" D-49                                              dimethoxybenzophenone                                                    5    mixed tetra-substituted                                                                          "Uvinul" 49D                                               benzophenones                                                            ______________________________________                                         Table II footnote: .sup.(1) Presently most desired substituted                benzophenone                                                             

Another class of derivitized benzophenones useful in the practice ofthis invention is characterized by the generic formula: ##STR4## where:

R³ is a lower alkyl radical.

An example of a substituted benzophenone of formula (4) is:2-ethylhexyl-2-cyano-3,3-diphenylacrylate (available from BASF under thetrademark "Uvinul N-539").

In the preceding formulas (3) and (4), the term "lower" has reference toa radical containing less than about 8 carbon atoms.

The contact angle exhibited by a silicone impregnant composition of thisinvention varies with the particular web which is to be saturatedtherewith. However, the contact angle of water is generally lower forthe non-impregnated side than the impregnated side. The combination ofthe processed web, the silicone polymer and the fluorochemical generallyproduces higher water contact angles than webs treated only withfluorochemicals. The performance of an impregnant composition may bedetermined by the nature of a previously applied saturant such as afluorochemical. Suitable starting compositions include 100% liquidcurable silicone rubber compositions, such as SLE5600 A/B from GeneralElectric, Mobay LSR 2580A/B, Dow Corning Silastic® 595 LSR and Silastic®590 which when formulated with substituted benzophenone as taught hereinwill form a contact angle of much greater than 70 degrees, and typicallyof 90+ degrees, with typical porous webs (such as fabrics) that have aresidue of fluorochemical upon (and within) the web from a priorsaturation.

The silicone polymer composition of this invention can also carryadditives into the three-dimensional structure of the web during thepressured impregnation. Further, it is preferable, that any additives bebound into the cured composition permanently as located in thethree-dimensional structure of the web. Particularly in the case offabrics, this desirably positions the additives mainly on surfaceportions of the treated yarns and fibers in positions where theytypically are beneficially located and maintained.

Control of the pressurized impregnation step can be provided at a numberof areas since the impregnation is sensitive to the viscosity of theimpregnant both at atmospheric pressure and at superatmosphericpressure. The ambient temperature affecting the impregnant as it isapplied, and the pressure-induced temperature changes occurring duringapplication of the impregnant also play roles in viscosity and thereforethe shear process. Of course, the chemical composition of the siliconepolymer impregnant composition of this invention also plays a role inthe shear process and assists in the formation of an internal coating.

The amount of silicone polymer impregnant utilized and the weight add-onthereof are again variable and dependent upon several things such as thetreated web, the desired end use of the web, cost and the like. Webweight add-ons can be as little as about 5 weight percent up to about200 weight percent of the untreated web. For producing breathable,water-repellant fabric webs of this invention, weight add-ons arepreferably in the range of about 10 to about 100 weight percent of theweight of the untreated web.

The fluorochemical saturant composition may also contain a bondingagent. The bonding agent can facilitate the bonding of the waterrepellant chemical and/or the impregnate to the three-dimensionalstructure of the web within which it is saturated. Mobay Silopren®bonding agent type LSR Z 3042 and Norsil® 815 primer are representativecompositions that can be used to facilitate bonding of the waterrepellant chemicals and/or impregnant to and within the web. Use of thebonding agents is not essential to the practice of this invention, butmay improve bonding of the fluorochemical and/or the silicone polymercomposition to fibers.

The fluorochemical particularly, and also the bonding agents when used,are preferably affixed to the three-dimensional structure of the webprior to a subsequent pressured impregnation. Complete affixing is notnecessary for the fluorochemical. The fluorochemical will apparentlyfacilitate the pressured impregnation of a silicone polymer compositioneven if the fluorochemical is not preliminarily fixed within or locatedwithin the web being treated. However, fixing, especially by sintering,appears to cause the water repellant chemicals to flow and to becomebetter attached to the three-dimensional structure of the web. In thisregard, a lesser amount of fluorochemical will remain in place better,and will better facilitate the subsequent pressure impregnation of thesilicone polymer, if the sintering or insolubilizing step is performedprior to such a pressured impregnation.

After fluorochemical saturation followed by silicone polymerimpregnation and curing, a web may have a surface contact angle ofgreater than about 70 degrees, and more typically greater than about 90degrees. Web impregnation pressures can involve transverse force orpressure in the range of tens to hundreds of pounds per square inch ofweb surface.

Similar to the functional qualifications achieved by the use of afluorochemical in the preferred saturating pretreatment step, thesilicone impregnant introduced by the pressured impregnation step can bedefined by its functional qualifications. For example, the siliconeimpregnant produces a contact angle with a fluorochemical treated web ofgreater than about 70 degrees. In measuring the liquid contact anglewith a fluorochemical treated surface and a silicone treated surface, itwill be understood that such a contact angle cannot exceed 180 degrees.The contact angle of a fluorochemical will be within a range of about 90degrees to about 180 degrees while the contact angle of the siliconepolymer will be within a range of about 70 degrees to about 180 degrees.

The contact angle exhibited by the silicone impregnant can be, ifdesired, qualified against the particular web saturated with theparticular fluorochemical saturant. The selection of a suitable siliconepolymer composition may be determined by the nature of the previouslyapplied fluorochemical saturant. The fluorochemical saturant andsilicone polymer compositions are, however, not critical to the practiceof this invention since wide respective compositional ranges may beinvolved. In particular, a substantially undiluted liquid silicon rubberwhich is available from suppliers, such as GE, Dow Corning, andMobay-Bayer, will characteristically form a contact angle of muchgreater than about 70 degrees, and typically greater than about 90degrees, with typical porous webs (such as fabrics) that have a residueof fluorochemical upon (and within) the web resulting from a priorsaturation.

The silicone polymer composition can carry additives into thethree-dimensional structure of the web in the pressured impregnationstep of the method of the invention. Further, the silicone polymercomposition, when cured, is capable of adhering to structural elements,fibers, yarns, and the like, and any additives dispersed therein. Thus,additives are positioned adjacent to or on surfaces of structuralelements, yarns, fibers and the like, in a position where they can bebeneficial.

Examples of additives that are dispersible in effective amounts in aviscous silicone polymer composition typically at a concentration ofabout 0.1 to 20 weight percent (based on total composition weight)include ultraviolet absorbers, flame retardants, aluminum hydroxide,filling agents, blood repellents, flattening agents, optical reflectiveagents, hand altering agents, biocompatible proteins, hydrolyzed silk,and the like. Hydrolyzed silk is a texturing agent that imparts asubstantially silky feel to a fabric treated in accordance with themethod of the invention regardless of whether or not such treated web orfabric is itself silk.

Examples of other silicone polymer dispersible agents include thoseaffecting thermal conductivity, radiation reflectivity, electricalconductivity, and other properties. For example, if a metallic sheenand/or thermal or electrical conductivity or infrared backgroundblending is desired, powdered metals may be dispersed therein.

The impregnation is sensitive to the viscosity of the silicone polymercomposition. The impregnation temperature affects the silicone polymercomposition by reducing or altering its viscosity. Shear-inducedtemperature changes occurring during application or during subsequentshear processing of the silicone polymer can affect viscosity. Thechemical composition of the silicone polymer also plays a role in thetreating process and can assist in the treatment of web structuralelements (including fibers) and the regulation of the filling ofinterstices and open cell voids.

Various machines and procedures can be used for performing the processof the invention. Illustrative machines and processes of use are nowdescribed which are suitable for use in the practice of this invention.

An embodiment of a machine suitable for accomplishing pressuredimpregnation in accordance with this invention is illustrated in sideelevational view in FIG. 4a. Two blades 200 and 210 in opposedrelationship to one another are provided in functional combination withmeans for providing a precisely adjustable gap therebetween throughwhich a web or fabric 300 is drawn while having a silicone polymercomposition 220 applied to either one or both surfaces thereof. Anenlarged side view of a typical blade 200 or 210 is shown in FIG. 4b.Dimensions A, B, C, D, and E are typically and exemplarily illustratedas, respectively, about 31/2 inches, about 11/2 inches, about 2 inches,about 1/2 inch, and about 5/16 inch. The narrow edge is preferablymilled to a tolerance of about 1/10,000 inch continuously along the edgesurface of each blade which is typically and illustratively about 38inches long. Each of the corners of the narrow edge is preferably andillustratively a hard (not beveled or ground) angular edge. Each blade200 or 210 is typically and illustratively made from carbon steel orstainless steel. A reservoir of silicone polymer composition is formedpreferably on one upper surface of the fabric 300 behind (relative tothe direction of fabric movement) an upper one of the blades 200 and 210which are mounted on a frame (not shown) so as to extend horizontally.As the fabric 300 is drawn through the slit orifice defined betweenblades 200 and 210, some impregnant becomes entrained on the web orfabric surface and moves through such slit orifice, therebyaccomplishing pressurized impregnation of web or fabric 300. The slitorifice gap is chosen preferably and illustratively to be slightlysmaller than the relaxed thickness of the starting web or fabric.

Referring to FIG. 4a, a second pressured impregnation station is seen tobe positioned downstream (relative to the direction of fabric movement)from the pair of opposed blades 200 and 210. At this station, a knifeblade 230 is provided which has an edge that presses against the web orfabric 300 to reintroduce the silicone polymer composition into thefabric 300. One side of blade 230 adjacent the edge thereof is stronglybiased against an adjacent cylinder or bar 240, which, in the embodimentshown, does not rotate. If desired, bar 240 can be journaled forrotational movement. As the fabric is moved between the blade 230 andthe bar 240, it is preferably uniformly compressed. Preferably, thecompression force is in the range of about 10 to about 500 inch pounds,although higher and lower forces can be employed. As the fabric 300passes over the edge of blade 230, it is drawn away at an angle from theblade edge under longitudinal tension. For example, longitudinal tensionin the range of from about 0.5 to 10 pounds per inch can be employed.Such pressured impregnation serves to distribute and reintroduce thepolymer composition in the web. Excess polymer composition is removed byblade scraping. Passage of the fabric 300 between the blade 230 and thebar 240 and over the edge of the blade 230 is believed to produce shearforces in the impregnant 220 (within the fabric 300) that facilitateflow and distribution thereof within the three-dimensional matrix of thefabric 300. Concurrently, blade 230 also scrapes excess silicone polymercomposition impregnant off the fabric's surface in contact with the edgeof blade 230.

Both the steps of fluorochemical saturation and of subsequent siliconepolymer composition impregnation are performable, if desired, inproduction volumes, and at speeds which can be typical of the so calledhigh end range of fabric finishing lines. The fluorochemical saturationis conveniently accomplished conventionally by using a padbath in whichthe fabric is run through a dilute treating bath followed by squeezerollers to remove excess liquid and overdrying. In general, any methodof applying the fluorochemical would be acceptable.

Another embodiment of a machine suitable for accomplishing pressurizedimpregnation in accordance with this invention is shown diagrammaticallyin FIG. 5 which also illustrates a process embodiment of this invention.At an impregnation head, pressurized introduction of the siliconepolymer composition into the web is first carried out. At a subsequentstage, controlled pressure reintroduction, distribution, and metering ofthe silicone polymer impregnant and recovery of excess impregnanttranspires using a shear knife or blade which applies transverse forceagainst the impregnated web laterally across the web. In a subsequentstage, further controlled pressure reintroduction and metering takesplace by means of a flexible blade, such as a so-called flex-knife orSpanish knife. Here, additional recovery of excess liquid impregnant isaccomplished. In all knife-applying states, the excess impregnantremoved is collected and preferably passed by a recycling system back tothe initial, pressured introduction stage to achieve process operatingeconomies. Still further successive impregnant pressure reintroductionstages may be used if desired. The direction of the arrows in thediagrammatic representation of FIG. 5 shows the general direction ofmovements in the region of the impregnation head, including the generaldirection of impregnant movement in the practice of such process.

The apparatus employed in the present invention functions first to applyand preferably concurrently impregnate a silicone polymer compositioninto a web under pressure. Such silicone polymer composition is thenreintroduced, distributed, and metered in a controlled manner in the webwith the aid of transversely applied shearing force and compressiveforce such that the impregnated composition becomes distributed in theweb so that an internal layer of silicone is formed while the fibers areat least partially enveloped while the interstices or open cells aresubstantially completely filled with the silicone polymer composition inthe region of the internal coating. During treatment, the web islongitudinally tensioned and the pressurized application andimpregnation and the subsequent shearing and compressive actions aresuccessively accomplished in localized zones preferably extendinggenerally laterally across the web (that is, generally perpendicularlyto the direction of such longitudinal web tensioning) using transverselyapplied force exerted locally against surface portions of the web duringeach impregnation and shearing operation. The web is conveniently andpreferably, but not necessarily, moved longitudinally relative to suchlaterally extending web processing zones. The impregnation, shearing andcompressing steps are preferably carried out successively orsequentially. Such zones are themselves preferably at stationarylocations while the web is moved, but if desired, the web can bestationary while the zones are moved, or both. The result is that thesilicone polymer composition impregnant flows into the web and isdistributed internally generally uniformly to a predeterminable andcontrollable extent.

A schematic side elevational view of another embodiment of a suitablepressurized impregnation machine for use in the practice of theinvention is shown in FIG. 6. This machine continuously moves alongitudinally tensioned web 60 successively through a pressureimpregnation station which incorporates a reverse roll coater havingrollers 10 and 11, a shear station which incorporates a shear knife 20,and a finishing station which employs at least one so called flex-knife(or Spanish knife) 30. Optionally, but preferably (for reasons ofprocess operating economics) excess silicone polymer composition that isremoved from web surfaces in the shear station and finishing station isreturned to the pressure impregnation station for reuse using liquidrecovery and recycle system 40. In the pressure impregnation station, asilicone resin impregnant 50 is contained within reservoir 51. Roller 12rotates in the indicated direction so that its circumferential surface,preferably a textured or gravure surface, picks up liquid 50 fromreservoir 51 and deposits it on the circumferential surface of roller 10across a controlled width gap 13 between rollers 10 and 12. Typically,gap 13 is actually less than the unencumbered thickness of the startingweb 60. Roller 10 also preferably has a textured or gravure surface.Roller 10, rotating in the roller arrow indicated direction, which isopposite to the direction of travel of web 60, applies the siliconepolymer impregnant to one surface of the moving web 60, which istypically a fabric. Roller 11 is urged with a compressive force againstthe back or opposed surface of web 60 and roller 11 rotates in adirection which is the same as that in which web 60 travels. Roller 11aids in achieving the desired pressured impregnation of web 60 byimpregnant from the surface of roller 10.

Referring to FIG. 6, the impregnant is believed to be introduced intothe web and into the interstices or open cells of the web 60 by the aidof a back-pulling or shearing action resulting from the distorting andpressuring of web 60 caused by rollers 10 and 11 rotating in the samedirection. This direction may be the indicated direction with roller 10rotating against the linear movement of web 60 indicated by webdirectional arrow 61, or all rollers 10, 11 and 12 may be reversed inrespective rotational direction so as to cause each roll to turn in anopposite direction relative to that direction which is illustrated bythe respective roller arrows in FIG. 6. Regardless of which side of web60 is back-pulled or subjected to shearing action by a reverse rotatingroller, the web 60 is stretched and distorted to pull open theinterstices of the web and to aid in impregnating web 60 with siliconepolymer impregnant 50. This distorting, and particularly thisstretching, is believed to facilitate the full and deep introduction ofthe impregnating liquid into the moving web 60.

The extent of pressured impregnation of the silicone polymer impregnant50 into the web 60 which occurs between rotating rollers 10 and 11 iscontrollable to some extent by such variables as the speed of rollerrotation, the pressure exerted by rollers 10 and 11 on web 60, thedurometer hardness and surface characteristics of each roll 10 and 11(particularly of the preferred textured or gravure surface of roll 10).However, the pressurized impregnation may also be carried out withrollers 10 and 11 which have finely milled, smooth circumferentialsurfaces. The viscosity of impregnant liquid 50 and the amount ofimpregnant liquid 50 transferred from roll 12 to roll 10 across gap 13may also be varied to regulate impregnation. Feed roller 12 preferablyrotates counter to application roller 10. The impregnant 50 can bemonitored to assure that its homogeneous composition is maintained. Ifdesired, the impregnant 50 formulation can be altered to adjust toprocess needs during a continuous treating operation.

The result of the pressured web 60 impregnation which is accomplishedbetween rollers 10 and 11 using a silicone polymer compositionimpregnant 50, which can have the viscosity or consistency of aconventional bathtub caulk composition, is to produce a web 60, orfabric, whose interstices or open cells are substantially completelyfilled with impregnant in the region of the internal coating. In, forexample, the case of a fabric, the impregnation extent can be such thatspaces (i.e., interstices or open cells) between the fabric'sfibers/filaments, or the fabric's yarn members (as the case may be) arefilled with impregnant 50. However, the amount of impregnant 50 which isthus introduced into web 60 can be much less than a saturation level;for example, the amount introduced can be insufficient even to coat orsubstantially completely envelope individual fibers of the web.Actually, the impregnant 50 can be relatively non-uniformly distributedin the web after such pressurized impregnation. The action of the shearknife 20 in the next zone of processing is such as to smooth out and tomake uniform the distribution of impregnant 50 in web 60. Also, theshear knife 20 helps regulate the amount of impregnant 50 that isallowed to remain in web 60.

After the shear zone, if desired, a top coat polymer can additionally beintroduced; for example, just before or after a flex knife 30. Byovercoating, for example, the original impregnant with a dilute or verythin second or top coat, a more tightly cross linked impregnated orenveloped product may be achieved, or surface properties of the productcan be varied or improved. For example, the top coating can comprise adilute dispersion of a fluorochemical fabric treating composition. In aweb treated therewith, such treatment enhances surface properties of theweb, such as by increasing grease or chemical penetration resistance, orsoil resistance, or the like. The dilute fluorochemical dispersion canbe applied by spraying, misting, or the like. Both treating agents thenenter a curing stage, which can be accomplished conveniently by passingthe treated web through an oven wherein the temperature and webresidence time are sufficient to cure both the fluorochemical andsilicone polymer impregnants to a desired extent, or by radiation, ifdesired.

The amount of silicone polymer impregnant actually introduced throughthe pressured impregnation, and into the preferably stretched openingsof the interstices of the web 60 is influenced by such factors as thevelocity of movement of web 60, the viscosity characteristics ofimpregnant 50, the compressive pressure exerted by roll 10 against roll11, the longitudinal tension exerted upon the tensioned web 60,impregnant distribution achieved by shear blade 20 and by scraper flexknive(s) 30, and the like. In particular, the impregnant reintroductionand distribution believed to be achieved by bar or shear knife 20 isachieved by the exertion of a pressure against moving tensioned web 60.The shear force and the temperature elevation due to such shear forceresults in the impregnant 50 flowing upon the three dimensionalstructure of the web 60 and the knife 20.

Preferably, the impregnant 50 is thixotropic. The flowing of theimpregnant 50 into the web 60 using controlled liquid rheologypreferably does not result at the time of impregnation in a fluidviscosity which is so low as to cause the impregnant to spread into andbe distributed substantially uncontrolled throughout the web 60.However, the flowing activity of the impregnant is preferablyaccomplished using an impregnant 50 which has a controllable rheologyand viscosity such that an impregnant 50 will achieve a desiredenvelopment of individual fibers of the web 60. Particularly when theweb 60 is a fabric, this envelopment is preferably a surrounding of thefabric's individual fibers with a localized layer or film of siliconepolymer while an internal layer is formed.

A plurality of web tension control devices 70 can be used in the regionof metering bar or shear knife 20 and in the region of reintroductionscraper flex knives 30 along web 60 in order to provide the capacity forprecision control of the tension exerted on web 60 and of thecompressive pressures and shear forces exerted on web 60 at the meteringbar or shear knife 20 and flexible knives 30.

As shown in FIG. 6, the machine preferably includes an impregnant 50recovery and recycling system which more preferably also includes afiltering subsystem, such system being diagrammatically represented andindicated by dashed line path 40. This system includes a collectiontray, or pan, 41, positioned under and behind the moving web 60 tocollect along the sides of web 60, the excess impregnating liquid as itis wiped from the web surface contacted by the metering bar 20 and/or bythe recovery knives 30 and passed laterally into pan or tray 41. Fromthe recovery collection tray 41, the excess impregnant 50 is pumped backthrough filter 42 into the reservoir 51 of the reverse roll coater forloading and distribution on the surface of roller 12, transfer to roller10, and reapplication to portions of continuously moving web 60. Theability to reuse the excess impregnant 50 wiped from the moving web 60rather than losing such impregnant within the process makes the entireprocess more economically attractive.

Another embodiment of a machine suitable for use in the practice of thisinvention is shown schematically in side elevation in FIG. 7. In thisembodiment, rollers 10 and 11 of the FIG. 6 apparatus are replaced witha combination of a reservoir 51, and a bar or shear knife 100. Thereintroduction bar or shear knife 100 pressurizes the impregnant liquid50 which is applied or deposited onto the moving web 60 from thereservoir 51 as a liquid or bath. The web 60 in effect constitutes aretaining wall for a part of the reservoir 51. The reservoir 51 thusfunctions to hold a pool of the silicone polymer composition impregnant50 against a surface of the moving web 60 which in the embodiment shown,is moving vertically upwardly. The bar or shear knife 100 functions toapply pressure or force upon the silicone polymer composition impregnant50 that was deposited on the web 60, thereby to cause the impregnant 50to penetrate the web 60 The knife 100 also serves to distribute and movethe impregnant in the web and to accomplish envelopment of the fibersthereof. Excess impregnant 50 is also scraped away by knife 100.Optionally, one or more of flex knives 100 function to furtherreintroduce, distribute the impregnant 50 and to envelope fibers of web60 while forming an internal silicone polymer coating within the web.The knives 110 can be considered to function in a manner which isequivalent to the knives 30 on the treated surface of web 50 in the FIG.6 apparatus.

Typically, any impregnant scraped from the moving web 60 by bar knife100 falls directly back into the reservoir 51. Impregnant scraped fromthe moving web 60 by scraper knife 110 is collected in sloping trough120 and returned by falling along the indicated dotted line path to thereservoir 51. Longitudinal tension control of the moving web 60 isregulated by tension control devices 70 (as in the FIG. 6 embodiment)from a region beginning after reservoir 51 and extending to an oven 80along the path of web 60 travel.

Relative to the FIG. 7 embodiment, the FIG. 6 embodiment is believed toexhibit a wider degree of control in the practice of the presentimpregnation process. Particularly, both the initial applied amount andthe successive pressurings of, a silicone polymer impregnant 50 areprecisely controllable. Relative to the FIG. 6 embodiment, the FIG. 7embodiment is characterized by the capability for operation at higherweb 60 transport speeds, typically at speeds characteristic of higherend commercial fabric finishing line operations. The embodiment shown inFIG. 6 is believed to be suitable for producing internally coatedfabrics when the fabrics are of the thicknesses characteristic ofgarments, and where deeply controlled pressured impregnation overdistances extending perpendicularly into and through a web of fabricgreater than about 1/16 inch is not generally required.

Illustrative parameters of the adjustments of the first embodiment ofapparatus shown in FIG. 6, are contained within the following threeTables III, IV and V. The first column of each Table lists a parameterthat is adjustable. For Table III, these parameters concern top roller10 shown in FIG. 6. For Table IV, these parameters concernreintroduction metering bar or shear knife 20 shown in FIG. 6. For TableV, these parameters concern web tensioning devices 70. The second columnof each Table indicates the typical respective ranges of parameteradjustment. The third column of each Table indicates the effect of suchadjustments on web impregnation.

                  TABLE III                                                       ______________________________________                                        MACHINE ELEMENT PARAMETERS                                                    First Stage Introduction Pressure Rollers:                                    Top Roller Adjust-                                                                        Variability  Effect of                                            ment Parameters                                                                           to Adjustment                                                                              Adjustment of Web                                    ______________________________________                                        Top roller pressure                                                                       0 to 500 lbs./                                                                             Delivery quantity,                                   down and in at an                                                                         linear inch  depth, residue                                       angle or in front of     presence both at lower                               roller                   yarn level and a                                                              fiber or filament                                                             level                                                Top roller surface                                                                        Smooth to    Degree of agitation                                              highly textured                                                                            and distortion or                                                             friction action                                      Top roller speed                                                                          50 to 1,000 RPM                                                                            Varies quantity by                                                            varying speed and                                                             distortion independent                                                        of web speed in relation                                                      to second and third stage                                                     systems                                              Metered Film                                                                              .05 mil thick                                                                              Contiguous film                                      Thickness on top                                                                          non-contiguous                                                                             delivery quantity                                    roller      film to 10 mil                                                                             controlling thicker                                              on roller    film presence and allows                                                      more impregnant to dam                                                        at either second or third                                                     stage                                                Lower roller                                                                              Low durometer                                                                              Low durometer                                        surface and material     material allows                                      composition surface to high                                                                            pressure from upper                                              strength metals                                                                            roller to be agitation of                                                     yarn bundles or fila-                                                         ment's metal surface                                                          causes more complete                                                          distortion and agitation                                                      of yarn and fiber/                                                            filament                                             ______________________________________                                    

                  TABLE IV                                                        ______________________________________                                        MACHINE ELEMENT PARAMETERS                                                    Second Stage Reintroduction Bar Knife:                                        Adjustment                                                                              Variability   Effect of                                             Parameters                                                                              to Adjustment Adjustment of Web                                     ______________________________________                                        Angle of bar                                                                            Bar knife faces                                                                             Angle effects shear                                   knife     forward to meet                                                                             forces on impregnate                                            web coming to and determines                                                  bar; bar knife                                                                              distortion or vertical                                          to web, bar   agitation as it                                                 faces away or relates to causing                                              racked back from                                                                            flow of impregnate;                                             web run direc-                                                                              can determine                                                   tion          reintroduction of                                                             impregnate by dammed                                                          quantity of impregnate                                Edge Shape                                                                              Knife very    Sharpness of knife                                              sharp         affects shear                                                                 forces. The                                                                   sharper and thinner                                                           the edge, the                                                                 greater the shear                                                             forces at the                                                                 contact edge                                          Pressure  Relates to web                                                                              Greater pressure                                                tautness      increases forces at                                                           contact edge                                          ______________________________________                                    

                  TABLE V                                                         ______________________________________                                        MACHINE ELEMENT PARAMETERS                                                    Adjustment  Variability   Effect of                                           Parameters  to Adjustment Adjustment of Web                                   ______________________________________                                        I. Second Stage Bars Below Web:                                               Web Speed   Range of      Affects the shear                                               machine speed forces at contact                                               possible      edge above, where                                                             impregnant is being                                                           forced into the web                                 Pressure on web                                                                           Range of motion                                                                             Tightens or loosens                                             of bar        tension on web                                                                which in turn                                                                 affects shear forces                                                          at contact edge                                     II. Third Stage Reintroduction Flex Knife:                                    Recovery system       Filters and pumps                                                             deliver impregnant                                                            back to first                                                                 introduction stage                                      ______________________________________                                    

A schematic, side elevational view of another suitable pressurizedimpregnation system or apparatus 73 for practicing the present inventionis shown in FIG. 12a. In this apparatus, a continuous web 74 is movedalong a web pathway from a supply roll 76 to a take-up roll 77.

In a first functional processing station 78, a silicone polymercomposition is applied to one face (here, the upper face 79) of web 74by a conventional reverse roll coater apparatus 81 wherein suchcomposition is applied to the surface of a reversely rotating (relativeto the direction of travel for web 74) coating roll 82 from a nip regionreservoir 83 formed between the coating roll 82 and a transfer roll 84(which rotates in the direction of travel for web 74, but whose surfacedoes not contact web 74). The web 74 is transversely compressed betweencoating roll 82 and drive roll 86 as it passes through station 78. Thus,the polymer composition is applied under a positive pressure againstface 79 by coating roll 82 which functions to cause the composition tobe impregnated into web 74. A present preference is to use a coatingroll 82 which has smooth, chrome plated surfaces.

Largely for purposes of controlling the alignment of web 74 with rolls82 and 86, the web 74 is pretensioned by coacting clutching rolls 87, 88and 89. After it passes over guide roller 91 on the web pathway fromsupply roll 76, the web 74 passes over roll 87, between rolls 87 and 88,around roll 88, and between rolls 88 and 89. The clutching rolls 87, 88and 89 are components of a conventional web clutching mechanism (notdetailed) which provides for adjustments between rolls 87, 88 and 89 sothat selective tensioning of web 74 is achieved along the web pathwaybetween the clutching rolls 87, 88 and 89 and the nip region 92 definedbetween rolls 82 and 86 with the intervening roller roll 93 being usedfor guidance of web 74. The clutching rollers 87, 88 and 89 alsofunction to smooth out and extend web 74 before it enters the coaterapparatus 81 so that in the apparatus 81, the web will have polymercomposition uniformly applied thereto.

After passing nip region 92 the web 74 is preferably highlylongitudinally tensioned along the web pathway extending from nip region92 to compensating and regulating coacting tension rollers 94, 95 and96. The tension rollers 94, 95 and 96 are components of a conventionalweb tension adjusting and regulating mechanism (not detailed) whichprovides for on-line, in-stream operator controlled adjustments betweenrollers 94, 95 and 96 that permit selective control of the tautness ofweb 74 particularly in the web pathway region from nip region 92 torollers 94, 95 and 96.

Along the tensioned web pathway region, the web 74 successively passesthrough each one of a series of processing stations 98, 99 and 100.

At each of the stations 98 and 99, a substantially non-flexible shearknife 101 and 102, respectively, extends laterally across web 74 withthe web 74 being entirely unsupported on the lower face 101 thereofwhich is opposed to upper face 79 and to the respective blades of eachshear knife 101 and 102. Both to control the amount and type of shearforce independently applied by each knife 101 and 102 the web 74 passesover each knife edge in a contacting relationship and three idler rolls105, 106 and 107 that are provided in a typically fixed (but off-lineadjustable) relationship relative to knives 101 and 102 as apparatus 73is operated.

Relative to the direction of web 74 travel, idler rolls 105 and 106 thusare positioned so that roll 105 is on the lead side, and roll 106 on thetrailing side, of knife 101 while idler rolls 106 and 107 are positionedso that roll 106 is on the lead side, and roll 107 is on the trailingside of knife 102. The angle of inclination or tilt of each blade 101and 102 relative to the vertical is adjustable over a wide range, but itis presently preferred to adjust the blade inclination angle for eachblade between about ±45° relative to the vertical with the bar 74 beinghorizontal. In the apparatus embodiment 73 shown, each respective bladeis functionally associated with a knife back support 108 and 109,respectively. Each support 108 and 109 permits its associated blade 101and 102 to be adjustably inclined in relation to the vertical relativeto a supporting frame (not shown).

Another adjustable variable is the amount of angular web depressionwhich, in the embodiment shown, extends downwardly, achieved by the webin its passage over the circumferential edges of adjacent rolls 105 and106 relative to knife 101, and in its passage over the circumferentialedges of rolls 106 and 107 relative to knife 102. Considering the placewhere the knife 101 or knife 102 contacts the web to be a hypotheticalpoint, the angle of the knife 101 or knife 102 relative to the web canbe in the range of about 30° to about 140°.

While it is presently preferred to employ shear knives 101 and 102 whichhave straight edges, it will be appreciated that shear knives havingsomewhat curved edges can be used, if desired. For example, whentreating a web which displays differential longitudinal stretchcharacteristics laterally thereacross in response to a uniform laterallyapplied warp tension, it appears to be possible to equalize the shearforces applied to a web by employing a suitably curved shear knife whichappears to compensate for such a differential stretch characteristic.

While it is presently preferred to employ shear knives 101 and 102 whichhave sharp edges, more preferably edges which are sharpened to a microedge uniformity of at least about root mean squared (RMF)8 shear knivescan be used which have dull or rounded edges.

While it is presently preferred to employ shear knives 101 and 102 whichare formed of steel, other materials of knife construction could be usedif desired, such as metal alloys, non-metallic composites, and the like.

Those skilled in the art will appreciate that the amount of shear forceapplied by a shear knife 101 or 102 transversely against a web 74 is afunction of many variables with probably the most important or principalvariables being the fluorochemical pretreatment, the silicone polymerviscosity and the longitudinal web tension (assuming a fixed spatialposition for idler rolls 105, 106 and 107 and shear knives 101 and 102during operation).

When a suitable and preferred level of applied shear force and webtensioning has been achieved to produce a product having envelopedfibers and an internal silicone coating, one can usually hear adistinctive sound in the region of a shear blade 101 and 102. This soundcan also be heard in the vicinity of shear blades being used in theoperation of other processes described herein. This sound can in fact beused by an operator as a rough guide as to whether or not he issucceeding in producing a silicone polymer impregnated productcontaining enveloped fibers and an internal coating.

Idler roll 105 also functions as a compensator roll for mechanicallyadjusting and controlling web tension after coating apparatus 81 andbefore knife processing begins. Also, conveniently and preferably theweb tension is sensed electronically, and then roll 105 is automaticallyraised or lowered to achieve web tensioning adjustments so as tomaintain a preset tension in web 74.

After passing over roll 107, the web 74 is passed over thecircumferential surface of a conventional padder roll 111.

Between the idler roll 107 and the padder roll 111, a flexible so-called"flex-knife" or "Spanish knife" 100 is positioned. Preferably, the bladeof this flexible knife 100 is inclined at an angle with respect to theweb 74 passing thereagainst so that the knife 100 exerts a compressiveforce against the face 79 of web 74 with opposed face 103 being entirelyunsupported. The angle with respect to a (hypothetical) perpendicularline extending into a (hypothetical) straight line extending from thecircumferential edge of roll 107 to the circumferential edge of roll 111can range from about 30° to about 140° for the adjustment of theinclination angle of the flex knife. To provide adjustability forflexible knife 100, knife 100 is functionally associated with a mountingbracket or back support 113 which in turn is adjustable relative to anapparatus frame (not shown).

In the embodiment shown in FIG. 12a, the padder roll 111 is not employedas a web 74 treating means.

After leaving the mechanical tension compensator rolls 94, 95 and 96,web 74 is under reduced or preferably minimal tension and is led along apathway which extends over spacer rolls 113 and 114. In the region overspacer rolls 113 and 114, and generally between tension roll 96 andidler roll 117, a platform 116 is conveniently positioned which canincorporate suitable instrumentation panels, operating controls and thelike so that an operator can observe the operation of the apparatus 73in the practice of the process of this invention and then control andregulate the same. A position which is suitable for operator observationof a web in progress that is located in the vicinity of the tenter frame118 is desirable because it has been observed that a web being processedcan experience some distortion owing to the forces exerted thereon.These distortions can be metered and observed and then the tenter frame118 adjusted by the operator so that, as the web passes therethrough,the web can be straightened or shaped either longitudinally orlaterally, as desirable or considered necessary for an individual web.If desired, the tenter frame 118 can be automatically operated to applytensioning forces to a web in accordance with a predetermined program,or the like.

The tenter frame 118 also provides the start of a new zone of limitedlongitudinal and transverse tensioning which extends forwardly along theweb pathway from tenter frame 118 through oven ? 19 to a tensioncompensator, here shown as utilizing three tension rolls 121, 122 and123 which are part of a conventional mechanical tension compensatorsubassembly which is similar in structure and function to thecompensator subassembly incorporating the previously described tensionrolls 94, 95 and 96. The tensioning longitudinally of web 74 as itpasses through oven 119 is employed to control the web 74 as it passesthrough oven 119 as regards web dimensional limits. This tensioning ischosen to be at a level which does not introduce significant distortioninto the web, yet web sagging is avoided, as from thermal expansion andelongation. Rollers (not shown) can be used in the oven 119 to avoidsagging and to maintain uniform heat exposure.

In addition to serving as tension regulating means, the rolls 121, 122and 123 also serve to provide a cooling pathway for the web 74 as itemerges from the oven 119 before it passes over guide roller 124 andinto take-up roll 77.

The oven 119 functions to cure the silicone polymer composition thusimpregnated into web- 74. Oven 119 can be operated with gas or otherenergy source. Oven 119 can extend for from about 12 to 20 yards, a 15yard long oven being convenient.

Curing temperatures of from about 320° to about 500° F., applied fortimes of from about 2 minutes to about 30 seconds (depending upon thetemperature) are desirable. If a curing accelerator is present in thesilicone polymer, curing temperatures can be dropped down totemperatures of about 265° F. or even lower (with times remaining in therange indicated).

In place of an oven, or in combination with an oven, a source ofradiation can be employed (electron beams, ultraviolet light, or thelike) to accomplish curing, if desired.

Less than the full heating capacity of the oven 119 can be used, ifdesired, or if full oven capacity is not needed, either longitudinallyor vertically. For example, only top heating or only bottom heating withrespect to the web can sometimes be used as compared to a combination ofboth top and bottom heating.

The take-up roll 77 is operating at approximately the same speed as thesupply roll 76. When the rotational speeds of take-up roll 77 are notsynchronized with rotational speeds of the supply roll 76, the tensionroll combination of rolls 121, 122 and 123 can be used to take up orreduce web slack, as the case may be.

Web transport speeds can vary widely; for example, from about 2 yardsper minute to about 90 yards per minute.

The process described above can be used in various forms or embodiments.Referring to FIGS. 12b and 12c, two alternate variations or modes areseen. In such views, similar components are similarly numbered but withthe addition of single prime marks thereto in the case of FIG. 12b anddouble prime marks thereto in the case of FIG. 12c.

In FIG. 12b, a further stage of web pressurization is introduced afterthe flex knife 112' and before the tenter frame 118'. Here, the web 74'after passage through the flex knife 112' is passed through the nipregion 126 existing between padder roll 111' and associated transferroll 127 where the web 74' is subjected to compression between suchrolls 127 and 111' for the purpose of achieving a better distribution ofsilicone polymer composition on web 74'.

After leaving nip region 126, the web 74' is retained under somecompression against roll 127 by means of retaining bar or roll 128 forsimilar purposes.

If desired, the roll 128 can be replaced by a flex knife (not shown)over whose edge the web 74' passes after departure or preparation fromroll 127. The flex knife can accomplish substantial further polymerdistribution in web 74'.

Referring to FIG. 12c, there is seen an embodiment where the web 74" ispassed through the nip region of rolls 111" and 127". Here not only isuse of the mechanical tension roll combination having rolls 94, 95 and96 (as in FIG. 12a) eliminated, but also the rolls 111" and 127" serveto end the region of high longitudinal tension in the stages of blade orknife application to web 74" and to provide the desired reduced pressurefor web passage through a curing station, here illustrated by oven 119"which succeeds the desirable and preferred intervening tenter 118".

Typically, and preferably, webs of this invention are characterized byhaving fiber development layers which range from about 0.1 to about 50microns.

A presently preferred web which is both flurochemical and silicone resintreated and which is breathable, water resistant and rewashable ischaracterized as being a longitudinally tensionable porous flexiblefibrous web having opposed, substantially parallel surfaces that arecomprised of associated fibers with interstices between the fibers or isa matrix having cells or pores therein. The web is substantiallyuniformly impregnated with a fluorochemical and thereafter impregnatedwith a silicone polymer composition, to form a web having an internallayer within the web wherein the outer surfaces of the web aresubstantially full of silicone polymer and the web is breathable andwater resistant or waterproof. At least a portion of the fibers or cellwalls are enveloped. At least one surface thereof is characterized byhaving a visual appearance which is substantially the same as the visualappearance of one surface of the starting porous web.

When the web has fibers comprised of a synthetic polymer, the polymer ispreferably selected from the group consisting of polyamides, polyesters,regenerated cellulose, cellulose acetate, and mixtures thereof.

Preferred webs of this invention are more specifically characterized byhaving a water drop contact angle in the range of about 90° to about160°; a rewash capability of at least about 3; a breathability of atleast about 35% of untreated substrate web; and a water repellencyrating of at least about 80 prior to washing.

A general process for making a porous web of this invention comprisesthe steps of: tensioning a flexible, porous web as above characterized,applying a curable silicone polymer composition to at least one websurface and then moving over and against one surface of the tensionedweb a uniformly applied localized shear force to: uniformly distributethe composition within the web, at least partially individually envelopesurface portions of at least some of said fibers or passageways throughthe web matrix with said composition in a desired web internal region.Thereafter, the web is subjected to conditions sufficient to cure thecomposition in said web. Curing is accomplished by heat, by radiation,or both.

A presently preferred process for making a fluorochemical and siliconeresin treated web having breathability, water resistance andrewashability which is adapted for continuous operation comprises thesuccessive steps of: impregnating the web with a fluorochemical,longitudinally tensioning the fluorochemical impregnated web whilesequentially first applying to one surface thereof a curable siliconepolymer composition and concurrently applying a transversely exertedlocalized compressive force against said surface, and moving over saidsurface of the web substantially rigid shearing means which exertstransversely an applied, localized shear force against said surface andwipes away exposed portions of silicone polymer composition on saidsurface, thereby forming an internal layer of silicone polymer whileenveloping at least some of the fibers or passageways through thematrix; and curing the silicone polymer composition in the web.

The fluorochemical impregnation operation is conveniently and preferablycarried out by the steps of: substantially completely saturating the webwith a solution or dispersion of a fluorochemical composition in acarrier liquid; compressing the saturated web to remove therefrom excessportions of said dispersion; and heating said web to evaporate thecarrier liquid therefrom. However, any convenient process can be usedfor accomplishing fluorochemical pretreatment of a web to be used inthis invention.

The following text concerns the theory of the invention as it is nowunderstood; however, there is no intent herein to be bound by theory.

The presently preferred polymer impregnant used in the pressureimpregnation and knife blade treatment of webs by this invention is anon-Newtonian liquid exhibiting thixotropic, pseudo-plastic behavior.Such a liquid is temporarily lowered in viscosity by high pressure shearforces.

One aspect of the invention is a recognition that when high forces areapplied to curable silicone polymer compositions, such as those asviscous as bathtub caulk, then the viscosities of these materials can belowered perhaps up to 99% or more. Conversely, when cured (polymerizedand/or cross-linked) these compounds increase in viscosity up to perhaps1,000,000% or more. The internal and external rheological control ofsilicone impregnant materials achieved by the present invention isbelieved to be of an extreme level even for thixotropes. When subjectedto shear force, the liquid silicone polymer composition can flow morereadily, perhaps comparably, to water. When subsequently subjected tocuring, the same liquid composition sets to a solid form which can havea consistency comparable to that of a hard elastomeric rubber.

The invention preferably employs a combination of: (i) mechanicalpressure to squeeze a silicone polymer composition impregnant into aporous web; (ii) a porous web pretreatment with a water repellentchemical, such as a fluorochemical, which is theorized to reduce thesurface tension characteristics of the web and create a favorablesurface contact angle between the silicone polymer composition and thetreated web which subsequently allows, under pressure and shear forceexerted upon an applied silicone polymer composition, the production andcreation of an internal coating or layer which envelopes fibers or linescell walls in a localized region within the web as a result ofimpregnant flow in the web; and (iii) a liquid silicone polymercomposition impregnant preferably having favorable rheological andviscosity properties which responds to such working pressures andforces, and in controllably impregnated into, and distributed in a web.This combination produces a web having the capability for a high degreeof performance. This product is achieved through pressure impregnationand applied shear forces brought to bear upon a web so as to causecontrolled movement and flow of a silicone polymer composition into andthrough a web. Preferably, repeated compressive applications of pressureor successive applications of localized shear forces upon the impregnantin the web are employed

By the preferred use of such combination, a relationship is establishedbetween the respective surface tensions of the impregnant and the web,creating a specific contact angle The impregnant responds to a waterrepellent fluorochemical pretreatment of the substrate so as to permitenhanced flow characteristics of the impregnant into the web. However,the boundary or edge of the impregnant is moved, preferably repeatedly,in response to applied suitable forces into the interior region of aporous web so as to cause thin films of the impregnant to develop on thefiber surfaces.

The word "thixotropy" refers herein to liquid flow behavior in which theviscosity of a liquid is reduced by shear agitation or stirring It istheorized to be caused by the breakdown of some loosely knit structurein the starting liquid that is built up during a period of rest(storage) and that is torn down during a period of suitable appliedstress.

Thixotropic behavior is preferably built into an impregnant used in theinvention by either polymer design or additive/filler design. Forexample, it now appears that thixotropic behavior can be accentuated byintroducing into a silicone polymer composition certain additives thatare believed to impart enhanced thixotropy to the resulting composition.A lower viscosity at high shear rates (during application to a web) isbelieved to faciliate impregnant flow and application to a web, whereasan impregnant with high viscosity, or applied at a low shear rate(before and/or after application) actually may retard or preventstructural element (including fiber) envelopment.

Illustratively, the practice of this invention can be considered tooccur in stages:

In stage 1, silicone polymer composition impregnant is prepared can bepurchased commercially and comes in typically two parts, designated as Aand B.

For example, in a silicone polymer composition as taught in U.S. Pat.No. 4,472,470, a base vinyl terminated polysiloxane is the A part, whilea liquid organohydrogensiloxane crosslinking agent is the B part.Certain remaining components, such as a resinous organopolysiloxanecopolymer and a platinum catalyst may (or can) apparently initially bein either part A or part B.

Stage 2 can be considered to involve the mixing of such a product'sparts with or without additives. Changes in viscosity can be obtainedand measured based on applied shear rates and shear stresses. Suchchanges can be experienced by an impregnant with or without additives.Up to a 99% reduction in viscosity of a liquid silicone polymercomposition is believed to be obtainable by the shear forces involved inthe mixing or infusion of a silicone polymer composition impregnant intoa web during, the elapsed applied combination of processing time,temperature, radiation, and/or chemical changes involved. Thereafter, avery substantial increase in impregnant viscosity is believed to beobtainable taking into account these same factors. Normally, the mostsignificant factor is now believed to be the mixing shear gradient thattypically reduces the viscosity of the impregnant about 50% below thestarting or rest viscosity.

Stage 3 can be considered to be the pressure introduction stage. Up to a99% reduction of the impregnant viscosity is believed to be obtainabledue to the applied shear forces, elapsed time, temperature, radiationand/or chemical changes. Thereafter, a 10,000% increase or even more inthe resulting impregnant viscosity is believed to be obtainable. In thisstage, curing of the impregnant can take place. Most commonly,impregnant viscosity is decreased during the pressure introduction stage3 by the application of shear forces.

Stage 4 can be considered to be the first stage internal matrixdispersing and reintroduction with metering, and also recovery andrecycle of excess impregnant. Typically, within this stage 4, the shearforces cause a temporary lowering of impregnant viscosity, causing it toflow upon and into the three-dimensional structure of the web. Theinitial visco-elastic character of the impregnant is typically theorizedto be recovered almost immediately after shear forces are removed.

Stage 5 can be considered to be a second stage internal matrixdispersing and reintroduction with metering and also recovery andrecycling of excess impregnant. The variations in the viscosity of theimpregnant are equivalent to stage 4. The viscosity of the impregnant isagain lowered causing it to flow within the web. Because of theapplication of repeated shear force induced reductions in viscosity, thethixotropic behavior of an impregnant may not undergo complete recovery,following each application of shear force and the viscosity of theimpregnant may not revert to its pre-impregnation values. The siliconepolymer composition impregnant is believed to have the capacity to formenveloping internal coating in a predetermined region wherein theinterstices or open cells are substantially completely filled within thethree-dimensional matrix constituting a web during the time intervalsthat the impregnant is caused to flow under pressure in and about matrixcomponents. In between these times, the impregnant may recoversubstantially all of its initial high viscosity, although perhapsslightly less so with each repeated application of shearing pressure orforce.

Stage 6 can be considered to be occurring just as curing is begun, andjust as heat is introduced.

Stage 7 can be considered to be occurring with regard to the exertion ofcontrol of curing. Typically, at least a partial curing (includingcross-linking and/or polymerizing), is obtained by relatively lowtemperatures applied for relatively short times, for example,temperatures under about 350° F. applied for under about 3 minutes,when, for example, light cotton, nylon or like fabrics are beingimpregnated.

FIG. 8, consisting of FIGS. 8a through 8d, shows four graphsillustrating four ways that could be used for plotting impregnantrheological behavior: (a) shear rate versus shear stress (uniformscales), (b) shear rate versus shear stress (log scales), (c) viscosityversus shear rate (uniform scales), and (d) viscosity versus shear rate(log scales), if desired, in the practice of this invention. Only thelog versus log scales are believed to be capable of encompassing a fullrange of values for the three indicated variables. The graphs representsome broad ranges of viscosity changes relative to shear stress thatcould be undergone by a given silicone polymer composition impregnantduring execution of a given pressured impregnation procedure as taughtherein.

For the purposes of the present invention, the term "surface tension"can be considered to have reference to a single factor consisting ofsuch variables as intermolecular, or secondary, bonding forces, such aspermanent dipole forces, induced forces, dispersion or nonpolar van derWaals forces, and hydrogen bonding forces. The strong primary bondingforces at an interface due to a chemical reaction are theorized to beexcluded from surface tension effects; however, it is noted that even asmall degree of chemical reactivity can have a tremendous influence onwetting effects and behavior affected by surface tension.

Surface tension is believed to induce wetting effects which caninfluence the behavior of a silicone polymer composition impregnantrelative to the formation of a fiber enveloped layer therewith in afibrous porous web. For example, adhesion is theorized to be a wettingeffect. Spontaneous adhesion always occurs for contact angles less thanabout 90°. However, for a combination of a rough surface and a contactangle over 90°, adhesion may or may not occur. In fact, roughnessbecomes antagonistic to adhesion, and adhesion becomes less probable asroughness increases.

Also, penetration is theorized to be a wetting effect. Spontaneouspenetration occurs for contact angles less than about 90°, and does notoccur for contact angles over about 90°. The roughness of a solidsurface accentuates either the penetration or the repellency action, buthas no influence on which type of wetting takes place.

In addition, spreading is theorized to be a wetting effect. Retractionoccurs for contact angles over 90° or over planar surfaces for anycontact angle. However, spontaneous spreading for contact angles lessthan 90°, especially for small contact angles, may be induced by surfaceroughness.

FIG. 9 is a schematic vector diagram illustrating the surface tensionforces acting at the vertex boundary line of a liquid contact angle on aplanar solid surface. It illustrates how surface tension forces might bemeasured between a silicone polymer composition impregnant and a fiberof a web (or a fabric) as treated by the invention.

FIG. 10 is a graph relating the contact angle over a smooth solidsurface as a function of θ and i that apply respectively, to adhesion (icosθ+1), penetration (i cosθ), and spreading (i cosθ-1).

Regions of adhesion versus abhesion, penetration versus repellency, andspreading versus retraction are shown by shaded areas. FIG. 10illustrates what is theorized to be the relationship of a siliconepolymer composition impregnant to silicone polymer composition solids ina treated web as regards such factors as adhesion, penetration,spreading, and retraction.

FIG. 11, consisting of FIGS. 11a through 11d, shows representativeviscosity profiles plotted on log viscosity versus log shear rate graphsfor (a) pseudoplastic flow, (b) distant flow, (c) pseudoplastic flowwith superimposed thixotropic behavior, and (d) laminar Newtonian flowthat erupts into turbulent flow at a critical transition point.

FIGS. 11a through 11d show a broad range of illustrative flowcharacteristics that could be demonstrated by silicone polymercomposition impregnants suitable for use in this invention usingpressured impregnation of a web as taught herein.

For purposes of this invention, the term "wetting" is used to designatesuch processes as adhesion, penetration, spreading, and cohesion. Ifwetting transpires as a spontaneous process, then adhesion andpenetration are assured when the solid surface tension exceeds theliquid surface tension. Surface roughness promotes these spontaneouswetting actions. On the other hand, no such generalizations can be madewhen the solid surface tension is less than the liquid surface tension.

Surface tension is measured as by S.T.L. units for liquid and by S.T.S.units for solids; both units are dyns/centimeter. When S.T.S. is lessthan S.T.L., then wetting is less ubiquitous and prediction of wettingbehavior is more difficult. However, by taking advantage of theliquid/solid contact angle that forms when a liquid retracts over asolid, it is possible to calculate with reasonable accuracy the wettingbehavior that can be expected. The reduction in liquid surface area canbe computed in terms of the contact angle that the liquid makes with thesolid surface. Contact angles are always measured in the liquid phase).There is a point of equilibrium where the surface tension forces becomebalanced.

By measuring the contact angle of a liquid on a solid, the wettingbehavior of the liquid impregnant can be measured.

The following examples are offered to specifically illustrate thisinvention. These examples are not to be construed as limiting the scopethereof, however.

EXAMPLE 1 Liquid Silicone Polymer Preparation

100 parts by weight of the curable liquid silicone polymer availablecommercially from Mobay as "Silopren® LSR 2530" was mixed in a 1:1ratio, as recommended by the manufacturer. A Hockmayer F dispersionblade at low torque and high shear was used to do the mixing. To thismixture were added 5 parts by weight of BSF "Uvinul 400" and 5/10 partsby weight Dow Corning 7127 accelerator, believed to be a polysiloxanebut containing an undisclosed active accelerated ingredient.

EXAMPLES 2-19 Liquid Silicone Polymer Preparation

The procedure of Example 1 was repeated with various other curableviscous liquid silicone polymer composition commercially available. Tothis product system is added a substituted benzophenone and otheradditives, the result of which are shown in Table VII below. All partsare by weight.

                                      TABLE VI                                    __________________________________________________________________________    Illustrative Silicone Resin Compositions                                                      Mixture Ratio                                                                         Substituted                                                                            Other                                        Example                                                                            Starting   of Packaged                                                                           Benzophenone                                                                           Additives                                    #    Silicone Resin                                                                           Components.sup.(1)                                                                    Name  Parts                                                                            Name       Parts                             __________________________________________________________________________    1    Silopren ® LSR 2530                                                                  1:1     Uvinul 400                                                                          5  7127 Accelerator                                                                         5/10                              2    Silastic ® 595 LSR                                                                   1:1     Uvinul 400                                                                          5  Syl-off ® 7611.sup.(2)                                                               50                                3    SLE 5100   10:1    Uvinul 400                                                                          5  Sylox ® 2.sup.(3)                                                                    8                                                   1:1                                                              Liquid BC-10                                                                             1:1                                                           4    Silopren ® LSR 2530                                                                  1:1     Uvinul 400                                                                          5  Hydral ® 710.sup.(4)                                                                 10                                5    Silopren ® LSR 2530                                                                  1:1     Uvinul 400                                                                          5  Silopren ® LSR                                                                       1                                                                  Z3042.sup.(5)                                6    SLE 5500   10:1    Uvinul 400                                                                          5                                               7    Silopren ® LSR 2540                                                                  1:1     Uvinul 400                                                                          5                                               8    SLE 5300   10:1    Uvinul 400                                                                          5                                               9    SLE 5106   10:1    Uvinul 400                                                                          5                                               10   Silopren ® LSR 2530                                                                  1:1     Uvinul 400                                                                          5  Flattening Agent                                                                         4                                                                  OK412 ® .sup.(6)                         11   Silopren ® LSR 2530                                                                  1:1     Uvinul 400                                                                          5  Nalco.sup.(5) 1SJ-612                                                                    50                                                                 Colloidal Silica.sup.(7)                     12   Silopren ® LSR 2530                                                                  1:1     Uvinul 400                                                                          5  Nalco ® 1SJ-614                                                                      7                                                                  Colloidal Alumina.sup.(8)                    13   Siliastic ® 595 LSR                                                                  1:1     Uvinul 400                                                                          5  200 Fluid.sup.(7)                                                                        7                                 14   Silopren ® LSR 2530                                                                  1:1     Uvinul 400                                                                          5                                               15   Silastic ® 595 LSR                                                                   1:1     Uvinul 400                                                                          5  Zepel ® 7040.sup.(10)                                                                3                                 16   Silastic ® 595 LSR                                                                   1:1     Uvinul 400                                                                          5  Zonyl ® UR.sup.(11)                                                                  1/10                              17   Silastic ® 595 LSR                                                                   1:1     Uvinul 400                                                                          5  Zonyl ® FSN-100.sup.(12)                                                             1/10                              18   Silopren ® LSR 2530                                                                  1:1     Uvinul 400                                                                          5  DLX-600 ®.sup.(13)                                                                   5                                 19   Silopren ® LSR 2530                                                                  1:1     Uvinul 400                                                                          5  TE-3608 ®.sup.(14)                                                                   5                                 __________________________________________________________________________     Table VI Footnotes:                                                           .sup.(1) Ratio listed is that recommended by the manufacturer.                .sup.(2) Syloff ® (registered trademark of Dow Corning) is a              crosslinker.                                                                  .sup.(3) Sylox ® 2 (registered trademark of W. R. Grace & Co.) is a       synthetic amorphous silica.                                                   .sup.(4) Hydral ® 710 (registered trademark of Alcoa) is a hydrated       aluminum oxide.                                                               .sup.(5) Silopren ® LSR Z/3042 (registered trademark of Mobay) is a       silicone primer (bonding agent) mixture.                                      .sup.(6) Flattening Agent OK412 ® (registered trademark of Degussa        Corp.) is a wax coated silicon dioxide.                                       .sup.(7) Nalco ® 1SJ612 Colloidal Silica (registered trademark of         Nalco Chemical Company) is an aqueous solution of silica and alumina.         .sup.(8) Nalco ® 1SJ614 Colloidal Alumina (registered trademark of        Nalco Chemical Company) is an aqueous colloidal alumina dispersion.           .sup.(9) 200 Fluid (registered trademark of Dow Corning) is a 100             centistoke viscosity dimethylpolysiloxane.                                    .sup.(10) Zepel ® 7040 (registered trademark of duPont) is a nonionic     fluoropolymer.                                                                .sup.(11) Zonyl ® UR (registered trademark of duPont) is an anionic       fluorosurfactant.                                                             .sup.(12) Zonyl ® FSN100 (registered trademark of duPont) is a            nonionic fluorosurfactant.                                                    .sup.(13) DLX6000 ® (registered trademark of duPont) is a                 polytetrafluoroethylene micropowder.                                          .sup.(14) TE3608 ® (registered trademark of duPont) is a                  polytetrafluoroethylene micropowder.                                     

EXAMPLE 20 Internally Coated, Fiber Encapsulated, Interstice FilledFabric Preparation

A complete, stepwise, application of the inventive method in theproduction of an encapsulated-fiber fabric was as follows.

The selected base fabric was TACTEL® (gold color) #612071 available fromICI Americas, Inc. through their agent, Arthur Kahn, Inc. This fabricwas 100% woven nylon. If desired, this and other fabrics may becalendered to modify surface texture.

The fabric was weighed and measured. Its initial weight is 3.1 ouncesper square yard. Its thickness equals 9 mils. The fabric was next washedwith detergent, rinsed thoroughly, and hung to air dry.

The fabric was soaked in water, wrung dry, and weighed. The waterretained was equal to 0.8 g water/g fabric.

The fabric was then treated with a water repellant fluorochemical, a 2%solution by weight of Zepel® 7040. In order to do so the fabric must bechemical in distilled water. This was because ##EQU2## The treatedfabric was then run through a wringer and air dried.

Next, the fabric was heated in an oven for 1 minute at 350° F. Thisheating sinters the water repellant fluorochemical. The fabric with itsfluorochemical residue is then run as in the preferred productionembodiment, FIG. 7, in a vertical configuration and is described below.The fabric is run from a roll that incorporates significant braking orclutching to initiate the tension required for controlled materialalignment and coating during application. The fabric web travels througha series of idler rolls ending at the application trough. As it passesthe application trough, it picks up a thin coating of siliconeimpregnant and then moves under a shear blade that is parallel to thefloor. The silicone impregnant is applied at 1.0 oz/sq. yd. andcontinues under a flex blade that is also parallel to the floor.

Multiple process stages of running the fabric with applied impregnantunder the blades are preferably made. The multiple process stages areimportant, and are normally necessary. The impregnant is Mobay 2530 A/Bin a 1:1 ratio and can be considered to be a viscoelastic liquid thatflows only under the shear forces resulting from the pressuredimpregnation. The impregnant is believed to return very substantially toits original viscous condition almost immediately upon release of thepressure. The impregnant was believed to flow a short distance withinthe matrix of the fabric during the short time that it was, because ofpressure shearing forces, of lowered viscosity. Therefore, a number of"flows" may be usefully generated in a number of passes in order toproperly distribute the impregnant in its preferred positionsubstantially encapsulating the surfaces of the fabric's fibers.

Finally, the impregnated fabric was run through a line oven, ofapproximately 10 yards in length, at 4-6 yards per minute, and was curedat 325°-350° F. It then passes through a series of idler rollers and isrolled up on a take-up roll, completing the tension zone. The resultantfabric has a non-tacky thin film of silicone that was internally coatedto form a fiber encapsulated, interstice-filled fabric.

EXAMPLE 21 Evaluation of Fiber Encapsulated Fabric Properties

The test results of the original versus the produced fiber encapsulatedfabric of Example 20 were as follows:

    ______________________________________                                        Fabric        Original Fabric                                                                           Encapsulated                                        ______________________________________                                        Spray Rating (1)                                                                            20          100 (reverse = 100)                                 Rain Test (2) Fail        Pass                                                Abrasion Test 1,800       3,200                                               (cycles) (3)                                                                  Moisture      Saturated   0.0 g                                               Penetration (4)                                                               Hydrostatic   1           2                                                   Resistance (psi) (5)                                                          MVTR (g/m.sup.2 /day)* (6)                                                                  4,414       2,362                                               Weight (oz/yd.sup.2)                                                                        3.1         4.1                                                 Amount Impregnated = 1.4 oz/yd.sup.2                                          ______________________________________                                                       Times Washed                                                                  Initial 5 ×                                                                              10 ×                                                                         15 ×                               ______________________________________                                        Laundering Test (7)                                                           (spray ratings)                                                               impregnated side                                                                             100     90       90   90                                       reverse side   100     90       90   90                                       unimpregnated treated                                                                        100     80       80   40                                       fabric                                                                        Accelerated Weathering Test (8)                                               Samples placed in QUV weatherometer for 72 hours.                             original = 7                                                                  impregnated side = 9                                                          reverse side = 8                                                              ______________________________________                                         Footnotes:                                                                    *Environmental chamber at 104° F. and 74% humidity.                    (1) The spray test was conducted in accordance with AATCC 221974. It          measures water repellency of a fabric sample on a scale of 0-100, with a      reading of 100 designating a completely water repellent fabric.               (2) The rain test was conducted in accordance with AATCC 351985. It           measures resistance of a fabric sample to penetration of water under          static pressure from a shower head of 3 feet/5 minutes. A fabric is           stormproof when less than 1.0 gram of water is absorbed by a standardized     blotter used in the test.                                                     (3) The abrasion test was conducted in accordance with Fed. Test Method       Std. 191 A, Method 5306. Abrasion resistance is measured by mounting a        fabric sample on a Taber Abraser Model 174 and measuring the number of        cycles before the fabric begins tearing apart.                                (4) The hydrostatic resistance test was conducted in accord with Fed. Tes     Method Std. 191A, Method 5512. The test measures a fabric sample's            resistance to water under pressure using the Mullen's Burst Test              apparatus. Test results are expressed in pounds per square inch at which      water beads penetrate the fabric.                                             (5) The moisture vapor transmission (MVTR) test was conducted in              accordance with ASTM E96B. The test measures the amount of moisture vapor     passing through a fabric sample in a controlled environment during a 24       hour period. The obtained MVTR figure is expressed in grams of                water/square meter of surface/24 hour day. The environmental chamber was      held at 104° F. and 47% humidity.                                      (6) The moisture vapor transmission (MVTR) test was conducted in              accordance with ASTM E96B. The test measures the amount of moisture vapor     passing through a fabric sample in a controlled environment during a 24       hour period. The obtained MVTR figure is expressed in grams of                water/square meter of surface/24 hour day. The environmental chamber was      held at 104° F. and 47% humidity.                                      (7) A laundering test of the conventional household type was performed.       Fabric samples were washed with Tide ® detergent. There was no drying     A spray test was subsequently carried out after each wash to determine th     effect of the washing.                                                        (8) The accelerated weathering test was conducted in accordance with ASTM     G53. Samples of original and impregnated fabrics were placed in the           weatherometer of QUV Company and results were compared. (All readings wer     based on a graduated color scale of 0-20; 10 designated the original          color, while 0 designated a white out).                                  

EXAMPLE 22 Description of Fabric Impregnation Through Scanning ElectronMicroscope Photomicrographs

FIGS. 3a, 3b and 3c were taken using a Cambridge 360 scanning electronmicroscope. The samples were cut using teflon coated razor blades,mounted on 1/2 inch diameter aluminum stubs, and coated with agold/palladium alloy.

FIG. 3a is a photomicrograph of the gold color Tactel fabric describedin Example 20. The surface of the material has been magnified 120 timesand shows that the cured silicone polymer impregnant is present as athin film, or coating, or layer within the material and envelopes atleast a portion of the fibers. The fiber bundles are somewhatdistinguishable in the weave, but each filament in the fiber bundles isnot individually distinct.

The sample in FIG. 3b has been magnified 600 times and shows thecross-section of a fiber bundle from the same Gold Tactel in FIG. 3a.The cured silicone polymer impregnant envelopes at least a portion ofthe fibers. The interstices or void areas between filaments in theregion of the internal coating are mostly filled or plugged by suchimpregnant. However, the web remains breathable and because of theimpregnant barrier is either water resistant or waterproof.

FIG. 3c is the side of the fabric in FIG. 1 opposite from which thesilicone polymer impregnant was applied. The silicone polymer impregnantis most readily apparent at the fiber bundle interstices and not visiblein the fiber bundles themselves.

EXAMPLE 23 Fiber Enveloped Fabric Preparation

The selected base fabric was Arthur Kahn TACTEL® (hot coral) #70146.This fabric is 100% nylon.

The fabric was pretreated at Cal-Pacific (a commercial finisher offabrics) with duPont ZEPEL® 6700.

The impregnant composition is Mobay LSR 2530 A/B in a 1:1 ratio=5%UVINUL® 400 (5% of total weight of Mobay LSR).

Impregnation of this composition was performed in a three stagecontinuous process using equipment as shown in FIG. 7 consisting of thefollowing procedure:

The composition was applied to the fabric at (a) a pressure of 3lbs/linear inch, utilizing (b) a shear (bar) knife at a high pressure,and at a 90° angle to the fabric (the edge of the knife is milledsharp). The rate of application is at approximately 1.0 oz/sq yd.

A flex knife was then applied at a 45° angle with the recovery systemutilizing gravity.

For both (a) and (b) above, the microweb pressure was applied at a lowweb speed on a roller system varied at from about 260-400 yards perhour.

Next, the fabric is cured using an upper oven (lower oven turned off) ata temperature of about 320°-330° F. The fabric was in the oven forapproximately 3 to 4 minutes The impregnant cures to a non-tacky thinfilm, as in the previous example.

EXAMPLE 24 Prior Art Silicone Polymer Treated Fabric

The fabric resulting from a prior art application of a viscous liquidcurable silicone polymer composition is shown in FIG. 2. Thephotographic view of FIG. 2 is at 150× magnification. It shows apolyester and cotton cloth blend into which Dow Corning 590 LSR siliconepolymer composition has been coated by a procedure of the prior art. Thefabric side shown in FIG. 2 is the top, or treatment, side, which wasthe fabric side upon which coating was accomplished.

As shown by the example of the treated fabric of FIG. 2, the prior artimpregnated fabric is characterized by a high degree of disorder. Alarge number of particulates (typical) appear to litter the surface ofthe fabric. A substantial portion of the area of the surface, whichappears to be a solid layer, is silicone polymer composition Certainyarn fragments can be observed to protrude through the surface of thissilicone polymer composition. Additionally, the silicone polymercomposition on either the polyester or the cotton fibers is not anencapsulation layer, but rather a matrix with the coated fibers being ingeneral disarray, probably from forces occurring during the indicatedprior art silicone polymer composition application procedure. Althoughsilicone polymer composition is present upon the yarn or fiber surfacesof the substrate, and certainly is present as a layer upon the exteriorsurface of the three-dimensional fabric body, the silicone polymercomposition has not controllably and individually encapsulated thefibers and left the interstices between fibers largely devoid of suchpolymer. In the prior art, a placement of silicone polymer compositionin a fabric is not controlled to such a degree so as to produce aproduct in accordance with the present invention.

EXAMPLE 25 Description of Fabric Impregnation Through Scanning ElectronMicroscope Photomicrographs

FIGS. 13a, 13b and 13c were taken using a Cambridge 360 scanningelectron microscope. The samples are cut using teflon coated razorblades, mounted on 1/2 inch diameter aluminum stubs, and coated with agold/palladium alloy.

FIG. 13a is a photomicrograph of the Tactel (hot coral) fabric describedin Example 23. The surface of the material has been magnified 120 timesand shows that the cured silicone polymer impregnant is present as athin film, or coating, or layer within the material and envelopes atleast a portion of the fibers. The fiber bundles are somewhatdistinguishable in the weave, but each filament in the fiber bundles isnot individually distinct.

The sample in FIG. 13b has been magnified 800 times and shows thecross-section of a fiber bundle from the same Tactel in FIG. 13a. Thecured silicone polymer impregnant envelopes at least a portion of thefibers. The interstices or void areas between filaments in the region ofthe internal coating are mostly filled or plugged by such impregnant.However, the web remains breathable and because of the impregnantbarrier is either water resistant or waterproof.

FIG. 13c is the side of the fabric in FIG. 1 opposite from which thesilicone polymer impregnant was applied. The silicone polymer impregnantis most readily apparent at the fiber bundle interstices and not visiblein the fiber bundles themselves.

In the next examples that involve accelerated weathering, abrasion,water repellency, moisture penetration, and rain testing, data isprovided for a Tactel fabric identified as Deva Blue. The fabric is 100%nylon, available from Arthur Kahn and identical in composition,preparation, and enveloping specification to that of the Hot Coralpresented in previous examples.

EXAMPLE 26 Accelerated Weathering Test

The results of weathering upon a treated web of this invention are shownin actual tested sample pieces comparing original fabrics withembodiments of the enveloped fiber fabrics of this invention.

In every case, the enveloped fiber fabric samples were found to havesignificantly better weathering characteristics than the originaluntreated fabrics as determined by accelerated weathering tests. Eventhe reverse side (compared to the treated side) of an enveloped fibernylon fabric of the Tactel® type was improved over the original fabric.In addition, the excellent "hand" of the enveloped fiber fabric wasfound to have been maintained after the accelerated weathering test.

The test performed conforms to each of the following performancestandards:

ASTM G-53 light/water exposure-materials

ASTM D-4329 light/water exposure-plastics

General Motors Test spec TM-58-10

ISO 4892 Plastics exposure to lab light

The procedure used for the accelerated weathering testing involvedsubjecting fabric samples to four hours of high-intensity ultravioletlight, alternating continuously with four hours of water condensationwetting the fabric in the dark. This alternating exposure (four hourson, four hours off) to high-intensity ultraviolet light and waterwetting simulates outdoor environmental conditions in a vastlyaccelerated manner, quickly degrading unprotected dyes and fibers.

The apparatus used for this test was a QUV Accelerated Weathering Testerfrom The Q-Panel Company, 26200 First Street, Cleveland, Ohio 44145.

The results obtained on some sample fabrics are expressed in thefollowing Table. In this Table, results are expressed in the form of"A/B" where A and B are numbers. The number "A" is the color rating on agraduated scale from 0 to 10. The number 10 equals perfect (original)condition where 0 equals a white color and a completely faded fabric Thenumber "B" is the number of hours of weathering transpiring when thenumber "A" rating was obtained

                  TABLE X                                                         ______________________________________                                        Accelerated Weathering Testing                                                                                Color Rating                                        Original           Reverse                                                                              (Rating/Hours)                                Orig- Fabric   Enveloped Side   10 = Perfect                                  inal  Weath-   Fabric    Weath- 0 = White                                     Fabric                                                                              ered     Weathered ered   Color Fades Out                               ______________________________________                                        1.  TACTEL ® Deva Blue                                                        9-420-6-1                                                                 10/0  3/159    8/159            After 159 hrs., envel-                                                        oped fabric signifi-                                                          cantly less weathered                                                         than original; original                                                       nearly white; envel-                                                          oped fabric still light                                                       blue.                                         2.  TACTEL ® Hot Coral                                                        9-420-6-2 (AKA 18)                                                        10/0  5/24     10/24     9/24   After 24 hrs., envel-                                                         oped fabric is signifi-                                                       cantly less weathered                                                         than original, as was                                                         reverse side.                                 ______________________________________                                    

EXAMPLE 27 Abrasion Resistance Testing

The results of abrasion resisting testing clearly show that envelopedfiber fabrics of this invention have superior wear characteristicscompared to the untreated original (starting) fabrics. In most cases,the enveloped fiber fabric samples underwent twice as many cycles as theuntreated samples without evidencing tearing in the samples. Suchresults can be explained by theorizing that the envelopment withsilicone polymer of the yarns and fibers comprising a fabric, providessuch treated yarns and fibers with a lubricity agent so that abrasiveaction was minimized and the integrity of the fabric was preservedsignificantly longer. The anti-abrasion character also applied to theminimized effects of one fiber rubbing against another fiber, or of oneyarn against another yarn.

This experiment compared the abrasion resistance of embodiments of theenveloped fiber fabrics of this invention with untreated fabrics.

The durability of each fabric test specimen was determined by the TaberAbraser. Each specimen is abraded for the number of cycles indicated.Comparisons were then made between the enveloped fiber fabrics of theinvention and untreated fabrics.

Specifically, this test method utilizes the Taber Abraser No. 174. Animportant feature of this abrader was that its wheels traverse acomplete circle on the test specimen surface. Thus, the surface wasabraded at all possible angles relative to the weave or grain of thespecimen. Comparisons of the enveloped fiber fabric to the untreatedfabric were based upon a scale 0 through 10, where 0 was a completelytorn specimen, and 10 was the new (or starting) sample.

Each test procedure used a single 7 inch diameter fiber enveloped fabricspecimen, and a single 7 inch diameter original (untreated) fabricspecimen. The procedure used was as follows:

1. A test specimen of the fiber enveloped fabric with a 7 inch diameterwas cut.

2. An equally-sized specimen of control (untreated) fabric was cut.

3. The fabric specimen was mounted on the rotating wheel securely andthe clamps were screwed down.

4. The counter was set.

5. The vacuum power adjustment was set. (For this experiment, vacuum wasset at 80.)

6. The abraser was started.

7. At the procedurally specified number of revolutions, the abraser wasstopped and each fabric sample was rated at a value between 0 and 10.

Illustrative results of the test on some sample fabrics are shown in thefollowing Table:

    ______________________________________                                        Abrasion Testing                                                              ______________________________________                                        Numeric Grade of Abrasion 0-10                                                0 -       Total failure of fabric specimen.                                             Fibers are torn apart.                                              5 -       Fabric specimen is starting to tear.                                          Fabric is noticeably thinner.                                       10 -      Original unabraded fabric specimen.                                 ______________________________________                                               UN-        ENCAPSU-                                                    SPECI- TREATED    LATED                                                       MENS   FABRIC     FABRIC     COMMENTS                                         ______________________________________                                        Hot    5          7          Untreated sample is                              Coral  1000 cyc.  1000 cyc.  starting to tear, and                            Tactel                       enveloped sample was                                                          still intact.                                    Deva   4          7          Visible rips in untreated                        Blue   1000 cyc.  1000 cyc.  sample. Enveloped                                Tactel                       sample fibers were                                                            frayed                                           ______________________________________                                    

EXAMPLE 28 Breathability Testing

This test procedure followed the Modified ASTM E96-B test.

As shown by the results of this testing in the following Table, thefiber enveloped fabrics of this invention were found to have highbreathability. This breathability was in excess of that needed to removethe average value of several thousand grams of perspiration generateddaily by the human body. The results for the fiber enveloped fabrics ofthis invention were generally superior to the corresponding resultsmeasured under the same conditions for prior art treated fabrics, suchas Gore-Tex® brand fabric.

Breathability of a fabric sample was determined by accurately weighingthe amount of water passing through such fabric sample under carefullycontrolled temperature and relative humidity conditions in anenvironmental chamber. The water weight loss from a cup whose mouth issealed with a fabric sample was expressed as grams of water vapor persquare meter of fabric per 24 hour day.

In an attempt to more realistically simulate what is actually occurringinside apparel during exercise, a specially designed test was performedto measure outward water vapor transport (MVTR) in a "Bellows" effect.The test simulates the high volumes of moisture and air that mix withina garment that pass outward through it as air is drawn in resultant fromactivity. The enveloped fabrics of this invention were found to provideincreased performance at higher activity, or air exchange level than isachievable with corresponding untreated fabrics.

The "Bellows" MVTR breathability test was run inside of a controlledtemperature/humidity chamber similar to the foregoing cup test. However,instead of a standard cup, each fabric sample was sealed over the opentop of a special cup which was provided with an air inlet aperture inits bottom, thereby allowing air to be bubbled up through the sealedcontainer at a controlled rate. A check valve at the air inlet operationprevents backup or loss of water from the container. The air bubblespassed upwardly through the water and out through the fabric samplemounted sealingly across the cup top along with the water vapor. Thefollowing Table illustrates some representation results obtained.

                  TABLE                                                           ______________________________________                                        Moisture Vapor Transport (MVTR)                                                                   MVTR.sup.(1)                                              ______________________________________                                        Fabric                                                                        Made by a method of the invention                                                                   13,600                                                  Enveloped fiber fabric, Hot Coral                                             Tactel ®                                                                  Commercial Products                                                           Gore-Tex/3-ply fabric 10,711                                                  ______________________________________                                         Table Footnote:                                                               .sup.(1) MVTR here references moisture vapor transport through a fabric       sample as measured by the "Bellows" test with air delivered to the bubble     at 2 to 4 psi air pressure, in an Environmental Chamber at 100 to             102° F. and 38-42% relative humidity. MVTR is expressed as grams o     water per square meter of surface per 24 hour day.                       

EXAMPLE 29 Water Repellency: Spray Testing

Water repellency spray testing is carried out according to AATEC TestMethod 22-1974.

The results of such testing show that the fiber enveloped Tactel®-typefabrics of the invention show excellent initial spray ratings initially,as do the original untreated fabrics which have been treated with waterrepellent chemicals such as fluorochemicals. Specifically, as theresults shown below demonstrate, after ten machine washes, the treatedside of a fiber enveloped fabric of the invention was found to remainhighly water repellent, while, on the reverse side thereof, the originalwater repellency rating was found to have fallen significantly. Thewater repellency spray rating on the untreated fabric fell even moredrastically. Excellent "hand" was retained after the test. It isbelieved that pretreatment with a fluorochemical having good waterrepellent properties can augment and even synergistically coact with thesilicone resin used to produce fiber enveloped fabrics of this inventionto produce superior spray ratings in such a fiber. The results are shownin the following Table.

This test method is believed to be applicable to any textile fabric,whether or not it has been given a water resistant or water-repellentfinish. The purpose of the test is to measure the resistance of fabricsto wetting by measuring the water-repellent efficiency of finishesapplied to fabrics, particularly to plain woven fabrics. The portabilityand simplicity of the instrument, and the shortness and simplicity ofthe test procedure, make this method of test especially suitable formill production control work. This test method is not intended, however,for use in predicting the probable rain penetration resistance offabrics, since it does not measure penetration of water through thefabric.

The results obtained with this test method are believed to dependprimarily on the resistance to wetting, or the water repellency, of thefibers and yarns comprising a fabric, and not upon the construction ofthe fabric.

This test involves spraying water against the taut surface of a testfabric specimen under controlled conditions which produce a wettedpattern whose size depends on the relative water repellency of thefabric. Evaluation is accomplished by comparing the wetted pattern withpictures on a standard chart.

The apparatus and materials employed for this test were an AATCC SprayTester, a beaker, distilled water, and the specimen fabrics.

The procedure followed for this test was as follows: a test specimen,which had been conditioned as procedurally directed, was fastenedsecurely in a 15.2 cm (6") metal hoop so that it presented a smoothwrinkle-free surface. The hoop was then placed on the stand of thetester so that the fabric was uppermost in such a position that thecenter of the spray pattern coincided with the center of the hoop. Inthe case of twills, gabardines, piques or fabrics of similar ribbedconstruction, the hoop was placed on the stand in such a way that theribs were diagonal to the flow of water running off the fabric specimen.

250 milliliters (ml) of distilled water at 27° C.±1° C. (80° F.±2° F.)was poured into the funnel of the tester and allowed to spray onto thetest specimen, which took approximately 25 to 30 seconds. Uponcompletion of the spraying period, the hoop was taken by one edge andthe opposite edge tapped smartly once against a solid object, with thefabric facing the object. The hoop was then rotated 180 degrees and thentapped once more on the location previously held.

The procedure and apparatus of this test were slightly modified from thespecifications, as follows:

1. The spray nozzle holes were slightly larger than specified, but theflow rate of the nozzle was 250 ml/30 sec., as required.

2. The number of taps of the hoop was two instead of one.

For each wash test, a fabric sample was washed using a warm wash/coldrinse cycle with one cup of Tide® detergent and dried at a hot/dry cyclein a dryer, unless otherwise indicated.

The test results were evaluated by comparing the wet or spotted patternon the fabric sample after tapping the hoop with the standard ratingchart. Results produced surface wetting, with no water completelysoaking through the test fabric sample. The numbers were ratings basedupon the standard chart. Such values are thus subjective deductions byan experienced experimenter.

                                      TABLE                                       __________________________________________________________________________    SPRAY TEST RESULTS                                                                       ENVELOPED-FIBER FABRIC OF THE INVENTION                                                    After 5  After 10                                     ORIGINAL FABRIC                                                                              Initial  Washes   Washes                                       Tactel ®   Enve-    Enve-    Enve-                                        Color &    After 4                                                                           loped                                                                             Reverse                                                                            loped                                                                             Reverse                                                                            loped                                                                             Reverse                                  Number Initial                                                                           Washes                                                                            Side                                                                              Side Side                                                                              Side Side                                                                              Side                                     __________________________________________________________________________    Deva Blue                                                                            100 10  90  100  90  70   80  50                                       9-420-6-1                                                                     Hot Coral                                                                            100 30  90  100  70  55   70  30                                       9-420-6-2                                                                     Gold Tactel                                                                          100 100 90   90  90  90   90  80                                       8-100-1                                                                       __________________________________________________________________________

EXAMPLE 30 Moisture Penetration Test

The results shown in the Table below demonstrate that all of the fiberenveloped fabrics of this invention test were significantly better thanthe original untreated fabrics with regard to resisting the penetrationof water under the test conditions used. After the test, the "hand" ofthe tested fabric samples remained excellent.

The purpose of this test was to evaluate how well a fabric stands up towetness under continuous pressure, such as kneeling on wet ground, orsitting in a wet chairlift, for a period of 30 minutes.

This test involves placing both a fabric sample and a standard blottersample on top of a water container which contains 700 ml of tap water.The fabric sample and the blotter sample are each then subjected to acontinuous pressure of 87 lbs. distributed evenly over 100 square inchesof surface area for a period of 30 minutes. After this time, a visualinspection of the fabric is made for any water penetration, and thepaper blotter is weighed to detect water gain or penetration.

The apparatus employed for each such test was one 20 inch diameteraluminum pan, one 87 lb weight distributed evenly over 100 square inchesof fabric, one paper blotter, 700 ml water, miscellaneous fabric scrapsfor cushioning and the test fabric sample pieces.

    ______________________________________                                        Paper blotter dry weight:                                                                          4.7      gm                                              Total weight applied to fabric:                                                                    87       lbs.                                            Pressure evenly distributed over                                                                   100      sq. in.                                         surface area of                                                               ______________________________________                                         ##STR5##                                                                 

The procedure observed for this test was as follows:

1. 700 ml tap water was placed in the round pan.

2. The fabric sample was placed with one side facing the water.

3. One piece of dry blotter paper was placed over the fabric to coverthe pan.

4. Scrap fabric was placed over the blotter paper to cushion the weight.

5. The 87 lb. weight was distributed evenly over the 100-square-incharea.

6. This assembly was left undisturbed for 30 minutes.

7. After this time period, the visual results were recorded.

                  TABLE                                                           ______________________________________                                        FIBER ENVELOPED FABRIC OF THE INVENTION                                       Fabric   Enveloped   Non-Enveloped                                            Sample and                                                                             Side of Fabric                                                                            Side of Fabric                                                                             Control                                     Thickness                                                                              Facing Water                                                                              Facing Water Fabric                                      ______________________________________                                        Deva Blue                                                                              No water    No water     Failure - total                             Tactel ®                                                                           penetration penetration  saturation of                               0.009 microns                                                                          through the through the  fabric and                                           fabric. No  fabric. No   blotter.                                             visible water                                                                             visible water                                                     spots.      spots.                                                            Paper weight =                                                                            Paper weight =                                                    4.7 gm      4.7 gm                                                            Water gain =                                                                              Water gain =                                                      0.0 gm      0.0 gm                                                   ______________________________________                                    

EXAMPLE 31 Rain Test

In this testing, the rain test procedure of AATCC Method 35-1985 wasfollowed.

The rain test results obtained demonstrate the clear superiority of thefiber enveloped fabric of the present invention as compared to theoriginal untreated fabric. The data in the Table below shows that fiberenveloped fabrics pass this test by allowing virtually no water to passtherethrough. This result is comparable to the results obtained withhigher cost so-called breathable waterproof fabrics currentlycommercially available in the market. In contrast, the original,untreated fabrics fail to pass this test because they demonstratecomplete saturation. The fiber enveloped fabric samples retain excellent"hand" after the test.

The purpose and scope of this ASTM test is to evaluate resistance of afiber enveloped fabric to water under simulated storm conditions. Thetest specifies that a test fabric is stormproof if less than one gram ofwater is absorbed by blotter paper with a shower head pressure of 3 feetexerted for 5 minutes. This test method is applicable to any textilefabric, whether or not it has a water repellent finish It measures theresistance of a fabric to the penetration of water by impact, and thuscan be used to predict the probable rain penetration resistance of afabric The results obtained with this method of test depend on the waterrepellency of the fibers and yarns in the fabric tested, and on theconstruction of the fabric.

This test involves a test specimen backed by a pre-weighed standardblotter The assembly is sprayed with water for 5 minutes undercontrolled conditions The blotter then is separated and weighed todetermine the amount of water, if any, which has leaked through thespecimen fabric during the test and has been absorbed by the blotter.

The apparatus and materials employed in each test were a modified raintester, blotter paper, water at 80° F.±2° F., a laboratory balance,8"×8" fabric specimens which had been pre-conditioned in an atmosphereof 65% (±2%) relative humidity and 70° F. (±2° F.) for four hours beforetesting, and tape.

The procedure followed for this test was as follows:

1. A 6"×6" paper blotter was weighed to the nearest 0.1 gm and placedbehind the test specimen

2. The test fabric with the paper blotter in registration therewith wastaped on the specimen holder.

3. A tube in the rain tester was filled with water up to the 3 footlevel. It was confirmed that water was flowing out of the overflow tubewhich maintains the 3 foot column of water.

4. The water spray distance from the tip of the nozzle to the specimenholder was measured and adjusted to 12 inches.

5. The specimen holder was left in place and the rain tester was turnedon for five minutes.

6. After the test period, the paper blotter was removed and reweighed tothe nearest 0.1 gm.

The results of the test on selected fabric samples are shown in Table:

                  TABLE                                                           ______________________________________                                        RAIN TEST: GRAMS OF WATER PENETRATING THE FABRIC                              ______________________________________                                                                 After 5   After 10                                   Fabric       Original    Machine   Machine                                    Sample       Not Washed  Washes    Washes                                     ______________________________________                                        Hot Coral Tactel ®                                                                     0           0         0                                          Deva Blue Tactel ®                                                                     0           0         0                                          Prior Art Treated Fabrics                                                     Ultrex ® 0           --          0.1                                      Gore-Tex ®                                                                             0           0         --                                         Original Fabrics-Water Repellant Chemicals Only,                              No Encapsulation                                                              Hot Coral Tactel/Failed-saturated                                             Deva Blue Tactel/Failed-saturated                                             ______________________________________                                    

EXAMPLE 32 Comprehensive Composite Measurement of Fiber Enveloped FabricPerformance

The preceding examples demonstrate the impressive performance of thefiber enveloped fabric of the fabric's invention in diverse areas. Yet,the results of each of these tests and performance capabilitiesexpressed individually fails to capture the comprehensively enhancedrange of performance capabilities of the fiber enveloped fabric of theinvention. For example, the impregnation process of the this inventionproduces a fiber enveloped breathable waterproof fabric that producesequal, or superior, test results over a broad range of differentperformances at a lighter, more insubstantial fabric weight compared,for example to the untreated fabric. In other words, less fabric can beused, or worn in the case of garments, in order to obtain equal orsuperior performance.

What is claimed is:
 1. A flexible porous web which has an internallylocated coating that is comprised of a curable silicone thixotropicshear thinning composition, said coating being positioned in anapproximately planar region extending through the web in a directiongenerally parallel to and spaced from at least one major surfacethereof, said web, upon curing the said curable composition thereof,being breathable and highly water repellant and exhibiting a hand andflexibility comparable to the hand flexibility of an untreated web. 2.The web according to claim 1 wherein said composition is nonelastomeric.3. The web of claim 1 wherein said composition is curable at roomtemperature.
 4. The web of claim 1 wherein said composition comprises athermoplastic material.